Thel 'Vadam

"The Arbiter. Maybe more than any other figure, a symbol of what the galaxy could one day become."

- Captain Thomas Lasky on Thel 'Vadam.

Arbiter Thel 'Vadam (formerly 'Vadamee) is the Sangheili kaidon of the House of 'Vadam and the last Arbiter to serve the Covenant. He continues to hold this title in the wake of its dissolution. Presently, he leads the Swords of Sanghelios, an alliance of keeps modeled after an ancient order of the same name, and is considered by many to be the formal leader of all Sangheili as the Kaidon of Unity.

Thel commanded multiple fleets during his service in the Covenant, most notably the Fleet of Particular Justice, of which he was Supreme Commander. This fleet mounted a successful attack on the human colony of Reach under his command and later fought the crew of the on Installation 04, the first Halo ring to be discovered by the Covenant and humanity. 'Vadamee was responsible for over one billion human casualties over the course of the decades-long war against the humans and the glassing of at least seven colonies. At the outbreak of the Great Schism, Thel became a leading figure among the Sangheili and aided the United Nations Space Command in its efforts to stop the High Prophet of Truth and his forces from activating the Halo Array. He and many Sangheili fought in multiple battles alongside the Spartan-II super-soldier, John-117 on Installation 05, Earth, and Installation 00 in the final weeks of the war.

Returning to Sanghelios after the war's conclusion, Thel became a symbol of Sangheili honor and resilience in the face of betrayal. He attempted to unite the feudal states across his homeworld in forming the first coalition government since the War of Beginnings. Despite his efforts, he met resistance from other Sangheili factions, who felt that his ideals and beliefs went against the traditional Sangheili values of Forerunner worship or that the peace treaty with the humans could not be trusted. This disagreement soon spilled over into civil war, and the Swords of Sanghelios became locked in conflict with other groups, primarily Jul 'Mdama's Covenant and the Servants of the Abiding Truth. He led the Swords to victory over these two groups, thanks in part to assistance from the UNSC.

Early life
"Thel 'Vadamee was born of noble blood. The legendary house of 'Vadam. His family's renown demanded great expectations for his military career. And he would meet them all."

- A San'Shyuum scribe about Thel 'Vadamee

Thel was born to the noble House of 'Vadam, rulers of the powerful state of Vadam on Sanghelios. In his youth, Thel was trained in the ways of fighting by his relative Lak 'Vadamee. He later joined the Covenant military, adding the "-ee" suffix to his surname according to custom. During the Human-Covenant War, Thel participated in the Covenant attack on the human Outer Colony of Madrigal in 2528. By 2535, he had at least one wife.

Within a short time, Thel achieved both the rank of Zealot and the title of shipmaster, and became kaidon of his state through the votes of Vadam's elders. Shortly after being promoted to shipmaster, Thel sustained an injury in the training ring due to a mistake. His family hushed up the incident, as well as the resultant visit by a physician, due to the Sangheili's cultural stigma toward doctors and medical operations. During his convalescence, Thel handmade an old-fashioned doarmir-fur shipmaster's cloak, and would later wear it as part of his shipmaster's attire to remind him that he could make grave mistakes if he let his guard down. Thel's role as kaidon was important for the House of 'Vadam, as he was tasked with continuing the reign of the powerful state of Vadam. Early in his rule, he was attacked by three Sangheili assassins wielding energy swords. He managed to kill all three without injury, and proceeded to appear before Vadam's elders to determine which had ordered the attack. Thel discovered that the assassination orders had come from the elder Koida 'Vadam, and after killing him, he ordered all of Koida's line to leave Vadam keep by sunrise.

Conflict at the Rubble
"It is a poor soldier who insists on seeing things not as they are, but as he wants them to be. One day reality hits, and his illusions fail him, and he dies stupidly. What honor is there in that?"

- Thel 'Vadamee

In 2535, Thel was sent to Charybdis IX with command over the vessel Retribution's Thunder to participate in the Battle of Charybdis IX, while being overseen by the High Prophet of Regret. He and several other Sangheili boarded the and attempted to access the vessel's navigation database, but it had already been purged. He left and witnessed the destruction of the ship before being called to Infinite Sacrifice, where he met the Prophet of Regret in person. Regret informed him of humans reportedly wielding modified Covenant weapons, a transgression he believed to be the doing of the Kig-Yar. He was then sent to the 23 Librae system to track down the source of the illegal weapons traders. For the mission, his ship was accompanied by the Kig-Yar vessel A Psalm Every Day, commanded by Shipmistress Chur'R-Mut and the Jiralhanae Chieftain Pellius.

Upon arriving at 23 Librae, Thel and his crew discovered the Rubble, a collection of asteroid habitats built by Kig-Yar and Insurrectionist humans working together. Almost immediately afterward, Thunder was attacked by A Psalm Every Day; Pellius had decided to betray Thel so that he could claim sole credit for the discovery. Thel and his crew were taken by surprise, allowing the traitorous vessel's second salvo to disable the Thunder's weapons, communications and engines. A Psalm Every Day escaped while Kig-Yar boarding craft and Spirits strafed the hull. Thel, increasingly frustrated, gave permission for his crew to abandon ship; this was a test to weed out the weaker Sangheili among his crew. Enemy Spirits destroyed the retreating craft in short order. Thel then ordered the destruction of the Retribution's Thunder, which killed the boarding Kig-Yar. Thel, however, survived and was captured, imprisoned on the Rubble along with most of the bridge crew. They ultimately managed to escape and hijack a Kig-Yar shuttle, taking them to another Kig-Yar vessel. On the surface of Metisette, Thel captured the leader of the warband, Reth.

Escaping Reth's clandestine Unggoy army, Thel returned to the Kig-Yar's vessel. Throughout the interrogation, the Sangheili were surprised by Reth's insistence that he was allying with the humans with the blessing of the High Prophet of Truth. According to Reth, the sale of the contraband weapons was a bluff in order to locate human worlds through tracking devices implanted in the weapons. Reth eventually escaped when a loyal Unggoy switched off his prison's energy barrier, fleeing via escape pod. Thel then turned his eyes to the Rubble, as a large skirmish between UNSC forces and Kig-Yar forces was taking place on the Infinite Spoils. The Sangheili and his crew boarded the Infinite Spoils and came face to face with Jai-006, engaging him in a brief fight. The Spartan then fled the ship with the other UNSC forces. Thel, surprised at the strength of the human warrior, stayed behind and commandeered the Infinite Spoils.

Thel managed to destroy most of the Rubble's mass drivers, but was left helpless when The Redoubt was destroyed and Habitat Exodus left the system. There was little else to do but wait for the High Prophets of Truth and Regret to arrive and recover him with his comrade, Zhar. Upon reporting the failure of the mission, Zhar attempted to kill the Prophets feeling helpless at the loss of his honor caused by the Prophet's scheming. Thel activated his energy sword and killed his friend without mercy. This act prompted Truth to spare his life, and he gave Thel command over a ship in the Fleet of Particular Justice.

Life as Supreme Commander
"One of the youngest to achieve the status of Shipmaster, and one of the youngest to gain the rate of Supreme Commander. In our campaign against the humans, few have risen to renown as 'Vadamee. World after human world, all laid low for sake of the Great Journey."

- A San'Shyuum scribe about Thel's achievements

At some point between 2535 and 2552, Thel 'Vadamee served as the Supreme Commander of the Fleet of Particular Justice. During this time he led the Covenant forces in the Battle of Camber. 'Vadamee and his fleet caught the UNSC forces completely unaware. He began his ground and orbital assault before most of the planet was aware of the attack. While 17 of his ships bombarded key defensive positions, 'Vadamee personally led an attack on the UNSC system headquarters. He first engaged the 3rd Battalion Reserves, who were caught completely unprepared. 'Vadamee ordered his men to wait for the humans to prepare to defend themselves before wiping out the entire unit. Throughout his time as Supreme Commander he was also responsible for the glassing of Bounty, Alluvion, Mesa, Greydowns, Kroedis II, and Estuary. He and his forces were responsible for over 1 billion human casualties—over 23,000 of them military personnel—and the destruction of 123 UNSC ships. ONI Section 3 attempted to kill him at different times, but failed each time resulting in the deaths of several operatives. Near the end of his time serving as Supreme Commander, he led the Covenant forces under his command to victory over the UNSC's greatest military stronghold. The Fall of Reach proved to be the highlight of Thel's service in the Covenant. As the battle ended, Thel ordered a flotilla of warships to follow the fleeing. The Autumn ' s course led them to holy Forerunner artifact Installation 04. After confirming that the ring was a creation of the "gods", the Prophet of Stewardship, the highest ranking political figure with the Fleet, immediately claimed authority over the operation, claiming the mission was now a religious matter. As Thel was unwilling to relinquish command with the Pillar of Autumn en route, and unable to contact High Charity to determine who held jurisdiction, a power struggle emerged between Thel and Stewardship for ultimate authority. As the Battle of Installation 04 wore on, the Prophet began subverting Thel, misappropriating military forces to secure facilities on the ring. Thel sent a single infantry unit to the Ascendant Justice to relieve the Prophet, but it was destroyed on approach. The Prophet threatened further punishment for any future affronts to his leadership. As Thel assembled a strike force to physically relieve the Prophet, the emergency beacon on the Infinite Succor was activated. Thel dispatched a Special Operations force to assess the threat and procure the Minister of Etiology. As Thel was about to leave with his strike force for Ascendant Justice, Spec Ops Commander Rtas 'Vadumee returned to the ship and revealed the results of his mission: the Flood had been unleashed on Halo.

With the situation deteriorating, Thel ordered the evacuation of all ships from the ring, as well as shooting down any vessel which failed to return clean bioscans. When Thel's force arrived on Ascendant Justice, he discovered that the Prophet of Stewardship had left for the Truth and Reconciliation. The crew of the Ascendant Justice acknowledged Thel's authority as Supreme Commander without hesitation. Unsurprisingly, Thel refused to come to the Steward's aid after its capture by the UNSC. These distractions were to cost Thel the battle, as SPARTAN-117 and Cortana successfully detonated, Pillar of Autumn under the nose of the Covenant's occupation. The detonation destroyed the Halo ring, ending the Battle of Installation 04. With little else to be done, Thel ordered his surviving ships to fall back from the destroyed Halo. This retreat was to save his remaining fleet from the Flood, but not his honor. In an act that further humiliated Thel, the Ascendant Justice was captured by John-117 and a small human boarding party. Shortly after his ships failed to pursue the Ascendant Justice, Thel was called before the Covenant High Council to answer for his failures.

During his time returning to High Charity, Thel wrote a Report on the Atrocity at Halo, detailing his view and apology for the ring's destruction alongside an analysis of the weaponry and vehicles of both the Covenant and Human ground forces.

Fall from grace and becoming the Arbiter
"Soon the Great Journey will begin, but when it does, the weight of your heresy will stay your feet, and you shall be left behind."

- The Prophet of Truth to 'Thel Vadamee at his hearing.

The loss of the holy Forerunner relic was an unforgivable failure in the eyes of the High Prophets and Sangheili Councilors. 'Vadamee was stripped of his rank, title, name, and honor, and branded a heretic for his failure to safeguard the Sacred Ring. The Mark of Shame was branded upon his chest, and he was sentenced to death. His corpse was to "be hung by his entrails" and "paraded through the city" as an example to others.

The Hierarchs, however, had a different fate in mind for Thel. Upon being brought before the High Prophets of Truth and Mercy, Thel was offered the choice of becoming the new Arbiter. Understanding that the office of Arbiter was itself a death sentence and seeking to regain his honor, Thel accepted.

Threshold gas mine
"What would you have your Arbiter do?"

- 'Vadamee to the Prophets

'Vadamee's first assignment as the Arbiter was to stop the heretic uprising based on a Forerunner gas mine in the atmosphere of Threshold. He was assisted by Rtas 'Vadumee, Special Operations Sangheili and Special Operations Unggoy. The operation was complicated by the unexpected escape of the Flood from the facility. During the chaos that followed, the Heretic leader Sesa 'Refumee sealed himself in a protected zone of the station. The Arbiter drove the Heretics out by cutting the cables from which the facility hung, causing the gas mine to fall. After crashing his Type-26AZ Banshee, the Arbiter fought his way through the Flood and surviving Heretics toward the station's hangar. Before Sesa 'Refumee could escape in a Type-31 Seraph, the Arbiter assassinated him, but not before the Heretic Leader revealed the source of his heresy. The Arbiter was surprised to discover that the Heretics had been aided by a Holy Oracle, the Monitor 343 Guilty Spark.

With the uprising suppressed, the Jiralhanae Chieftain Tartarus extracted the Arbiter and used the Fist of Rukt to capture the Oracle. His actions, which involved throwing the Oracle into the Type-52 Phantom recklessly, angered the Arbiter's religious sensibilities. With Tartarus, he left the gas mine via Phantom, as High Charity and the fleet departed the Threshold system.

Battle of the Quarantine Zone
"We shall cut into the heart of this infestation, retrieve the Icon, and burn any Flood that stand in our way!"

- Rtas 'Vadumee during the Battle of Installation 05

Aboard High Charity, Arbiter Thel 'Vadamee witnessed the replacement of the Sangheili Honor Guardsmen with the Jiralhanae as a result of Regret's assassination at the hands of the human Demon. Though distressed by change, and voicing his concerns to the Prophet of Truth, 'Vadamee made no further comment, as he has found out that the Covenant found another Halo. The High Prophets, who were surprised by both the fact that 'Vadamee had escaped from the Threshold gas mine and that he helped recover the Monitor Guilty Spark (the "Holy Oracle" to whom they inquired about Halo), decided to send him to Installation 05's "Quarantine Zone" to retrieve the "Sacred Icon". This holy relic was needed to activate Delta Halo and begin the Great Journey. On the way to the surface via a Phantom captained by Tartarus, Thel learned from Jiralhanae Chieftain that it was the Demon, the very same one responsible for Installation 04's destruction, who assassinated Regret.

Thel made his way through the Sentinel Wall (with a few surviving Unggoy and Kig-Yar) to deactivate the Library's quarantine shield, fighting a number of Sentinels and Enforcers, eventually passing by dead Jiralhanae on the way. He eventually deactivated the shield, but before Tartarus could pick him up, an Enforcer fired on his Phantom forcing him to break off. The situation was soon complicated when it was discovered that the Flood was running loose throughout the Wall and fighting the Sentinels. He progressively made his way on foot, briefly bearing witness to Human Marines being overrun by the Flood, who were slowly overwhelming the facility. Eventually, Thel made it to the other side of the Sentinel Wall, just as a Sentinel manufacturing facility was shot down by a Wraith mortar. Just as the Arbiter engaged the Flood on the ground, several drop pods landed with Special Operations Sangheili aiding him in his rendezvous with a very surprised Rtas 'Vadumee, who commanded the Sangheili to hold off the Flood until Phantoms could drop in reinforcements, and after a tough fight, they did.

It was then when the Arbiter filled the Spec Ops Commander on the former's mission to find Halo's Sacred Icon. Rtas pledged his help and ordered his troops to accompany Thel, but not without warning him to not underestimate the Flood. The Arbiter then made his way through various structures and canyons where Sentinels and Enforcers were fighting Flood who commandeered numerous vehicles such as Ghosts, Wraiths, Warthogs, Specters, and even a Scorpion, before traversing through the same Sentinel Manufacturing facility he saw get shot down earlier. Eventually, Thel and Rtas found a Gondola that would take them straight to the Halo's Library, where the former's objective was located. However, they discovered that humans have commandeered another gondola and are heading for the same destination. But with incoming Flood approaching from behind, the Spec Ops Commander stays behind and holds them off while the Arbiter takes the Gondola ahead with remaining Sangheili reinforcements. Wave after wave, the Flood attacked, but the Arbiter and his allies managed hold them off until the Gondola reached its final destination.

The Arbiter proceeded into the Library, encountering the remains of a battle between UNSC Marines, Sentinels and Flood combat forms, and witnessed Commander Miranda Keyes and Sergeant Johnson retrieving the Index. Using his armor's active camouflage, he stalked Johnson and Keyes. Leaping out of the shadows, 'Vadamee surprised Johnson, knocking him unconscious after a brief tussle. Keyes attempted to shoot Thel, but was quickly overpowered and disarmed. Tartarus then arrived and captured Keyes by using his hammer's gravity manipulation abilities, claiming the Index for himself. Tartarus informed Thel about the Jiralhanae's intended genocide of the increasingly "incompetent" Sangheili. Thel angrily proclaimed that the High Prophets would kill him for this treachery, only to be horrified that this treachery was sanctioned by the High Prophets themselves. The Chieftain then knocked the stunned Arbiter into a pit leading to the depths of Installation 05.

The Control Room
"Tartarus, the Prophets have betrayed us."

- Thel 'Vadamee's last attempt to convince Tartarus of the truth

The Arbiter was rescued from his fall by the Gravemind, the central intelligence of the Flood, and brought to its lair. It was here that the Arbiter met John-117 for the first time. Bringing forth the assimilated Prophet of Regret and 2401 Penitent Tangent, the Gravemind attempted to convince 'Vadamee that the Halos were weapons of destruction, not a path to transcendence, a position which John supported. However, the Arbiter was resistant, though his attention was drawn when the Gravemind mentioned the possibility of everything perishing "as they did before." In order to "show the truth" to the resistant Arbiter, the Gravemind teleported him to one of two likely spots it believed the key needed to stop the Halo's firing would be located.

The Arbiter was teleported to the vicinity of Delta Halo's Control Room. Observing firsthand the results of the Prophets' betrayal, the Arbiter joined forces with a band of Special Operations Commandos and quickly became a leader in the separatist movement. This small unit wasted little time in massacring the Jiralhanae responsible for executing the Sangheili Councilors. Eventually, Thel met Rtas 'Vadumee, joining forces to reach a. Near the Scarab, the Arbiter managed to rescue several separatist prisoners, as well as a group of UNSC Marines including Sergeant Avery Johnson. Johnson negotiated a tenuous alliance with the Arbiter in order to prevent Tartarus from activating Installation 05. Given the extreme danger posed by the ring, they both agreed that Tartarus had to be stopped at all costs. Johnson led the offensive, using a captured Scarab to eliminate ground units while Thel provided air support with a Type-26A Banshee. Together, they punched a hole through Covenant lines and reached the Control Room of Installation 05.

'Vadamee fought several Jiralhanae Honor Guardsmen before facing Tartarus, who had forced Miranda Keyes to activate Installation 05. Attempting to open Tartarus' eyes, Thel asked 343 Guilty Spark what Halo's true purpose was. The Monitor replied that the Halos were built "to destroy all sentient life within three radii of the galactic core," as a weapon of last resort against the Flood. The Forerunners had not transcended into gods, but rather died as a final sacrifice to ensure the defeat of the ancient parasite.

With this revelation, which confirmed everything that the Gravemind and John-117 had tried to tell him, the Arbiter lost any remaining faith in the Great Journey and attempted to convince Tartarus to see reason. The Chieftain however, remained loyal to the Prophets. In the battle that followed, the Installation was activated. With the firing process enabled, the Arbiter, with sniper support from Johnson, killed Tartarus after a prolonged firefight. Miranda Keyes then rushed to remove the Index, preventing the activation of the array.

New objectives
The shutdown, however, activated a failsafe system; the rest of the Halos were set to standby mode, and could only be activated remotely from what Spark informed them was "The Ark". After the Arbiter asked him its location, Spark gave them coordinates to Earth.

The release of the Flood from the ring, however, would put their plans to get to Earth on hold: the Arbiter would once again rendezvous with 'Vadumee, now shipmaster of the recently-captured assault carrier Shadow of Intent, flagship of the separatists' fledgling Fleet of Retribution. Together, they formulated a plan for sterilization and quarantine. Spark remained with the fleet to coordinate containment efforts while the Arbiter, Keyes and Johnson raced back to Earth aboard one of the fleet's vessels to warn humanity and to locate the Ark.

Like many Sangheili after the Great Schism, 'Vadamee abridged his surname to "'Vadam", symbolizing his resignation from the Covenant.

Return to Earth


"Were it so easy."

- Thel 'Vadam comments on the challenging prospect of killing John-117, and vice versa

'Vadam, Johnson, and Keyes arrived at Earth on or before November 15, 2552, taking up residence in the Crow's Nest base near the supposed Ark. After Truth's arrival two days later, and Chief's subsequent bailout from his command ship, 'Vadam, Johnson and several of his allies discovered the Master Chief's point of impact in Tanzania. When John regained consciousness, he attempted to kill 'Vadam with Johnson's sidearm. Johnson quickly informed the Spartan that the surviving Sangheili had allied with humanity after the Chief's last encounter with them. The Chief took Johnson's word, and 'Vadam assisted the Master Chief through the jungles near Mount Kilimanjaro, guiding him through the dense forest to the dam site. He then aided the Chief and the other UNSC forces during the defense of Crow's Nest from Truth's forces.

Battle of Voi
"Quickly! Let us find their ship. Make short work of this abomination!"

- The Arbiter on the arrival of the Flood

Thel rejoined John-117 at the docks, shortly after the Master Chief cleared the road to Voi of Covenant by destroying a Scarab. The two then attacked a section of the Covenant mechanized presence defending the area around the Forerunner Portal, which took them through a Traxus warehouse and in a confrontation with a pair of Mgalekgolo who sided with Brutes. Along the way, he cursed at a preaching hologram of Truth and declared that he will never again be shamed, cementing his newfound hatred toward the last surviving Hierarch of the Covenant, and still fuming over his betrayal and lies.

Opening a hole in the Covenant anti-air defenses, Lord Hood's remaining ships assaulted the Prophet of Truth's Forerunner Dreadnought. The airstrike was insufficient to destroy the ancient Keyship, and the activated artifact formed an enormous slipspace portal through which Truth and the Covenant fleet retreated. Before Lord Hood could consolidate the scattered human resistance, a Flood-infested Covenant cruiser transitioned out of Slipspace and crashed into the city, infesting a significant area in and around Voi.

The Arbiter and the Master Chief proceeded to cauterize the local area of the Flood, battling their way to the cruiser to overload the crashed ship's engines and destroy the source of the infestation. They made their way through the same warehouse they fought Covenant, only to bear witness to the Flood's reanimation of various corpses, both UNSC and Covenant, and carved a swath through the nightmarish outbreak. They were aided by a handful of surviving Marines before they came a cross a lone marine who was deeply traumatized by his encounter with the Flood, claiming he "helped" his squad by killing them.

As they made their way outside, John and Thel saw a Sangheili fleet, led by Shipmaster Rtas 'Vadum, emerge from slipspace to assist the humans in cleansing with the Flood, with the flagship carrier, Shadow of Intent, deploying a Special Operations squad to reinforce the Spartan and the Arbiter. From his newly-arrived Sangheili comrades, 'Vadam learned of the fall of High Charity and how a single cruiser had escaped the station's blockade, and was perturbed by how so little ships were now all that's left of their fleet, and even more so due to the fact that the Flood has evolved. The Arbiter assisted the Chief in clearing a path to the crashed cruiser, where they fought more Flood, including the newest pure forms that emerged from the wreckage, and learned that both Sangheili and UNSC leadership believed Cortana were aboard the downed Flood ship. While Thel and his fellow Sangheili made sure no Flood chased John, the Spartan entered the wreckage and retrieved Cortana, giving Rtas 'Vadum the opportunity to glass Voi and the surrounding areas to prevent the Flood from spreading.

Calm before the Storm
"If your construct is wrong, then the Flood has already won."

- The Arbiter on severity of events for humanity

Before and after being extracted from a Flood-infested Voi, Thel proved instrumental in moderating tensions between humanity and Sangheili, as the two races that had only recently been dedicated to each other's destruction. While Rtas 'Vadam callously advocated for the glassing of Earth to contain the Flood, Thel argued for a surgical strike on the landmass surrounding Voi.

Conferring aboard the Sangheili flagship Shadow of Intent, the allies learned from a message sent by the AI Cortana (which was repaired by 343 Guilty Spark), that the Flood were on their way to Earth. However, she claimed that the Gravemind was unaware of the Portal at Voi, and that there was a solution to the Flood on the other side; one that would eliminate the parasite once and for all without the need to fire the entire Halo Array. After the message's conclusion, the Sangheili chose to follow the Covenant fleet and deal with the Brutes and Truth. Tensions quickly rose with Lord Hood wishing to make the UNSC's stand on Earth, and Rtas gravely claiming that Earth would not survive the Flood. Thel supporting John's desire to pursue Truth and attack the Flood preemptively, claiming that if Cortana was wrong, then there would be no way to stop the Flood. After the decision was reached, the Sangheili allowed at least two UNSC frigates, including the Forward Unto Dawn, to accompany them through the portal and find Cortana's solution to the Flood.

Battle of the Ark
"The Prophet will die by my hands - not theirs!"

- The Arbiter on the Flood entrance to the battle



Arriving at the Ark, the Arbiter joined the Master Chief at the entrance of a local Cartographer facility to clear their way, shortly after the Sangheili annihilated Truth's Covenant fleet. Once there, they learned of Truth's location, as well as the forces he had deployed to the Ark's surface. When the group was attacked, the Arbiter joined the battle for air superiority, instructing John to follow 343 Guilty Spark to a nearby location for extraction.

With the destruction of the Covenant fleet, Rtas 'Vadum's carrier positioned itself near the Ark's Citadel - where Truth planned to remotely activate the rings. Commander Keyes led a three-pronged assault on the shield generators protecting Truth's citadel, with the Arbiter leading a Sangheili squad to deactivate the second tower, while the Chief would handle and first and Johnson the third. While both John and Thel succeeded in deactivating their towers, Sergeant Major Johnson failed to deactivate the third generator due to heavy Jiralhanae resistance. After the Chief made his way to the third tower, the Arbiter landed his forces at the third tower to support the Master Chief in successfully deactivating the final generator and shutting down the barrier, pushing through packs of Jiralhanae, a swarm of Yanme'e, and a pair of Mgalekgolo along the way.

With the barrier disabled, Shipmaster 'Vadum prepared to bomb Truth's position, but High Charity suddenly exited Slipspace and crashed into the Ark. In its plummet to the surface, High Charity scattered a barrage of infection capsules which crippled the carrier. The Arbiter led his forces in conjunction with the Marines to clear the third tower of Flood, with the Chief's assistance. As a security measure, the Arbiter escorted a distressed 343 Guilty Spark to reconnoiter the damage inflicted to the Ark by the Flood, leaving his Sangheili with the Chief to push on to the Citadel.

Death of Truth
"The Prophet of Truth"

- Thel 'Vadam

With the Covenant, including two Scarabs, guarding the Citadel defeated, Thel and John entered the Citadel, with the latter making clear that the Prophet of Truth would die by the Arbiter's blade, not the Flood who were scaling the Citadel's walls. They saw Truth broadcast his "faithful" and intending to activate the Halo Array with Johnson as a captive. As the Spartan and the Arbiter reach the top of the elevator shaft leading to the Citadel's control room, the Flood Gravemind unexpectedly formed a tentative alliance with them, claiming that it would cooperate with them in order to kill Truth and abort the firing of the Halo Array. Fighting through the remains of Truth's forces, this unlikely alliance eventually approached the location of the last High Prophet of the Covenant, briefly mourning the death of Miranda Keyes.

The Arbiter furiously approached Truth, who had been infected by the Flood and was slowly undergoing mutation, and declared his dogmatic claims about the Great Journey would not last. The Gravemind spoke through Truth, informing Truth that he was deluded to think he could achieve godhood, and claimed he would be "food, nothing more". It was then that Thel declared that he would have his vengeance upon a Prophet, not a disease, but not before forcing Truth to see John deactivate the Halo Array, with Truth expressed one final defiance as the "voice of the Covenant". With little hesitation, Thel "silenced" Truth, by impaling him with his energy sword before his Flood transformation could progress. At that moment, the leader of the Covenant fell dead with John looking on, but they were suddenly faced with the betrayal of the Flood, which now no longer faced any obstacles in killing the two and going on to consume the galaxy.

Destroying the Flood
"This is our fight. And I will see it finished."

- Thel 'Vadam to his fellow Sangheili

After a desperate escape from the Flood, the two soldiers witnessed Cortana's solution to the Flood: the construction of a new Halo ring that was meant to replace the recently destroyed Installation 04. As this replacement ring was not linked to the rest of the network, it could be fired safely, destroying every remaining Flood Pod infector in its radius, without harming humanity or the Covenant client races back in the Milky Way galaxy. The Arbiter, Johnson and Rtas 'Vadum evacuated all UNSC and Sangheili forces from the Flood-infested Ark while John went to rescue Cortana from High Charity, as she had the index from the first Halo ring. Some time later, Thel arrived on High Charity shortly after John set it to self-destruct, using an M7057 flamethrower to cover their escape.

The two then escaped on a D77H-TCI Pelican as High Charity exploded behind them. The Pelican flew past the Shadow of Intent, which has successfully evacuated all surviving Humans and Sangheili from the Ark, with the Thel declaring to Rtas that he will see the fight against the Flood be finished and decided to accompany his newly-befriended Spartan ally as their Pelican crashed onto the snowy cliffs of Installation 08. Scaling through the icy caverns, the pair approached an exact replica of the original Halo's control room as multiple Flood dispersal pods rained down around them and poured countless combat forms and pure forms around them. Aided by the Halo's sentinels, and eventually Johnson armed with a Spartan Laser, the Chief and the Arbiter made their way up the ziggurat fighting numerous Flood forms floor by floor. As they reached the top, the enraged Gravemind made one last defiant effort to kill the two soldiers, dropping countless forms to swarm and kill them, but they were unsuccessful as they rendezvoused with Sergeant Major Johnson and entered the structure as more dispersal pods were landing outside. Once the trio approached the control room, Thel stayed to cover the door as they heard a multitude of Flood closing in from behind.

343 Guilty Spark suddenly appeared in the control room, but the Monitor betrayed them after realizing that an immediate activation of the incomplete ring would destroy it and damage the Ark. In the battle that followed, the rampant 343 killed Johnson and knocked the Arbiter out of the room. After the destruction of 343, and a solemn Cortana's activation of Halo via the Index, Thel expressed sorrow over Johnson's death, noting his sacrifice would not be forgotten. Making their way outside, with Halo shaking and exploding all around them, they fought more Flood and the now-hostile Sentinels, and backtracked the path Johnson took along the canyons walls in order to escape on the Forward Unto Dawn. Once John, Thel, and Cortana travelled through a pulse generator, they found a Warthog left behind by Johnson, and resolved to escape the crumbling Halo. It was a long drive through skirmishes of Flood and Sentinels and falling debris all around, but the trio succeeded in reaching the Forward Unto Dawn and escaped the Ark and Halo just before it fired. Before departing to the bridge, Thel and John nodded to each other, a moment of mutual respect between warriors. This would be the last time 'Vadam would see the Chief for several years, as he then exited the hangar, and made his way to the bridge, while Chief and Cortana stayed behind and guided the frigate to its jump point, but the slipspace portal collapsed as Forward Unto Dawn transitioned.

The aft end of the ship, with John-117 and Cortana aboard, was sheared off and left adrift in unknown space. The bow section, containing 'Vadam, completed the jump and crash-landed on Earth, where he was rescued. The Covenant Empire had ceased to exist, and Thel began the first steps to bring his people into a new future.

Leader of the Sangheili
"Rtas 'Vadum"

- Thel 'Vadam

Thel acted as a voice of reform to the Sangheili, uniting the keeps under a new planetary government, the Swords of Sanghelios. Returning to his homeworld, he planned to visit each state to make his case for permanent peace with the humans they had battled for so many years; one of these would be a meeting in the state of Mdama. It was here that he announced that he no longer felt he was an Arbiter, but simply a Kaidon. He told the elders that if any of them disagreed with him strongly enough, they could attempt an assassination as per Sangheili tradition.

These reforms did not meet with universal approval. By January 2553, there was great dissent among disparate Sangheili parties, especially from the more devout believers in the Forerunners' divinity. Some, such as Avu Med 'Telcam and his Servants of the Abiding Truth, saw the Arbiter as a false leader that has betrayed their pre-Covenant worship of the Forerunners and sought to preemptively strike at humanity, fearing they would retaliate for the war. Additionally, many devout believers regarded Thel a "false Arbiter", stating that his very existence was heretical as he did not sacrifice himself the battle as was traditional of Arbiters in the Covenant. Others opposed 'Vadam not on religious grounds but due to his alliance with humanity, considering the notion of peace with the humans hopeless and that they could not be trusted. Thel argued with logic, they had not only failed to defeat humanity in the end, but attacking them would bring Sanghelios to ruin after the sundering of the Covenant had left their people without the technical expertise to replace lost warships, or maintain their own infrastructure.

In the midst of these events, the Office of Naval Intelligence secretly assisted 'Telcam in creating an insurrection against 'Vadam, in order to keep the Sangheili divided and prevent them from threatening the UNSC.

Cessation of war
"Lord Hood"

- Thel 'Vadam



In February 2553, 'Vadam met with Fleet Admiral Lord Terrence Hood, along with Captain Serin Osman, Corporal Vasily Beloi and Dr. Evan Phillips in the state of Vadam on Sanghelios. There, he and Lord Hood discussed the fragile state of both species, as well as a treaty to formalize the peace. Hood then invited 'Vadam to a memorial service on Earth, and in return 'Vadam invited Dr. Phillips to study Sangheili history and culture on their homeworld.

On March 3, 2553, 'Vadam was present at the dedication of the memorial to those humans lost during the Covenant War. He was thanked by Hood for standing alongside John-117 "to the end"; knowing the resilience of the Spartan first hand, Thel expressed doubt as to the soldier's death. The Arbiter departed for Sanghelios aboard the Shadow of Intent along with Rtas 'Vadum, to ensure the security of their people.

Blooding Years


"The assault on Vadam must begin now."

- Avu Med 'Telcam signaling the start of uprising

In March 2553, the Arbiter greeted Phillips in Vadam. Phillips requested a tour of Sanghelios' most ancient cities to which Thel approved and assigned Phillips an escort, Cadan 'Ilmir. Not long after, they lost Phillips in Ontom after dissident Jiralhanae detonated an explosive in the state. In the wake of this uprising, 'Telcam and the Servants of the Abiding Truth launched their attack on the state of Vadam. 'Vadam was later contacted by Lord Hood who informed him that he could recover Phillips and quell the rebellion. 'Vadam was doubtful of his offer but graciously accepted his help. Despite 'Telcam's ship having been shot down early in the battle, the situation on Sanghelios intensified as reinforcements from like-minded keeps arrived to attack Vadam keep. Lord Hood arrived on Sanghelios onboard humanity's most powerful ship,. The Arbiter was caught off guard and as his own reinforcements failed to arrive on time, he reluctantly accepted the UNSC's help in fending off the attackers. Infinity decimated the rebel forces while posed as a Kig-Yar pirate ship and covertly destroyed some of 'Vadam's ships, leaving the Arbiter with a Pyrrhic victory. After the battle, 'Vadam was in talks to visit UNSC Infinity.

Later in 2553, 'Vadam sent 'Vadum on missions to the frontier colonies to give the shipmaster a much needed break from combat. However, during these missions, 'Vadum encountered a surviving Covenant Prelate and minister—Tem'Bhetek and Boru'a'Neem who led Jiralhanae forces. With the help of Tul 'Juran of Rahnelo, 'Vadum was able to defeat the two San'Shyuum and their forces. Afterwards, 'Vadum contacted 'Vadam and briefed him on the events that transpired. 'Vadam attempted to convince his friend to return to Sanghelios for a break, but 'Vadum wished to continue his missions in the frontier to search for the remaining San'Shyuum, to which the Arbiter agreed to. At 'Vadum's suggestion, 'Vadam also amended the Swords of Sanghelios' protocol to allow the enlistment of females in the military after 'Vadum personally witnessed the skill 'Juran showed in combat.

In March of 2555, the UNSC contacted 'Vadam after discovering that the Halo Array had been set to fire in three weeks. The countdown had been initiated from the Ark, and the UNSC requested the Swords of Sanghelios' aid in re-activating the portal at Voi in order to dispatch a team there to disable the activation sequence. As he was preoccupied with the ongoing civil war, 'Vadam sent Usze 'Taham and N'tho 'Sraom, along with several other Sangheili aboard corvette Mayhem and a Huragok to aid the humans.

Peace talks
"He's had every reason to hate us, both before and after the war. The old Covenant races probably would have come after humanity a long time ago if he hadn't insisted we were important to their survival."

- Captain Thomas Lasky about the Arbiter before the meeting on Ealen IV.

In 2558, Thel 'Vadam attempted to enter into peace negotiations with the Jiralhanae, with the UNSC Infinity being assigned to escort him. On March 5, 'Vadam met with Lord Hood and the Jiralhanae Chieftain Lydus on Ealen IV. During the negotiations, Covenant mercenaries led by Shipmaster 'Gajat attacked the delegates. Captain Thomas Lasky, Commander Sarah Palmer, and the Spartan-IVs defended the delegation and evacuated them from the chamber. Lydus accused 'Vadam of betraying him, but Thel reassured him that he had no part in the attack as he killed a Kig-Yar Sniper attempting to assassinate Lydus. When their evacuation ship was destroyed, the security detail proceeded to escort the delegates to a nearby parts depot.

Inside the repair depot, 'Vadam notified Hood and the rest of an old fortified redoubt in which they could take refuge in. Captain Lasky ordered Palmer and the protection detail to escort the delegation to the redoubt. As the party escaped the depot, they were intercepted by a Covenant Lich. Palmer quickly acted and threw her helmet filled with grenades and destroyed the Lich. The delegation stayed back as Fireteam Jackknife and their bodyguards went ahead to ensure the redoubt was safe for them to use as shelter. However, as the delegates entered the redoubt, Spartan Scruggs of Fireteam Jackknife—who had betrayed his team—ambushed the group and held Hood hostage. 'Vadam queried Scruggs on what his demands were; Scruggs stated that they would discuss them once his associates arrived. With the Covenant bearing on the site in force, the ambassadors' security detail discovered a craft they could use to evacuate. Thanks to the sacrifices of Fireteam Bailey, the delegation, Lasky and the surviving Spartans made it aboard Infinity, which rallied the feuding Sangheili and Jiralhanae fleets and forced 'Gajat's forces into retreat.

Sanghelios Global War and Swords victory
"Hunt them to the last. Today we extinguish the Covenant's light forever!"

- Thel 'Vadam during the Battle of Sunaion.

Ambush at Nuusra
"Thel 'Vadam"

- Sangheili

Following Jul 'Mdama's death on Kamchatka in October 2558, the remaining forces of 'Mdama's Covenant regrouped and launched an assault on Sanghelios. 'Mdama's Covenant used the city of Sunaion over Csurdon Sea as a staging point to launch an attack against Swords of Sanghelios territory, though the Arbiter countered this move by establishing a forward operating base in the ruins of Nuusra on the sea's coast. However, 'Mdama's Covenant attacked first and laid siege to the Swords of Sanghelios base on Nuusra, pushing back 'Vadam and his forces to the Elder Council Chamber.

Meanwhile, John-117 and the rest of Blue Team had apparently gone rogue to pursue Cortana and the UNSC dispatched Fireteam Osiris to retrieve them. After Blue Team escaped Osiris aboard a Forerunner Guardian that Cortana had entered into slipspace to an unknown location, Doctor Catherine Halsey and Spartan Sarah Palmer proposed for Osiris to utilize the Guardian located near Sunaion to follow Blue Team. Not wishing for the UNSC to get too engaged in the Sangheili civil war, Lasky had Infinity travel to Swords of Sanghelios and arranged for Osiris to be escorted to the Arbiter's position by Swords of Sanghelios soldiers. Osiris fought their way through many Covenant entrenchments between their landing point and the Arbiter's location within the Elder Council Chamber, while 'Mdama's Covenant started to overwhelm the Swords of Sanghelios at the camp; several corpses from these ambushes were witnessed by Osiris on their way to the Arbiter. With help from surviving Swords of Sanghelios soldiers, the Spartans eliminated 'Mdama's Covenant forces around the chamber and moved inside to find the Arbiter; Osiris arrived at his position just as he was single-handedly killing several Covenant Sangheili. Contacting Mahkee 'Chava, Osiris was extracted from the chamber along with the Arbiter, and a number of other surviving Swords, by a Type-57 Phantom.

Finding a hidden Constructor
"The Covenant soldiers will hear the Guardian wake from its slumber, they will look up over the bodies of their brothers, through the smoke of their burning city, they will look to the horizon as their holy idol rises from the sea and forsakes them. And that is when the Covenant dies."

- Thel 'Vadam assuring his troops in victory

Returning to the Arbiter's primary camp in Nuusra with Palmer and Halsey, 'Vadam and Osiris leader Spartan Jameson Locke spoke about using Sunaion's Guardian to pursue Blue Team, with the latter greeting and thanking the former for his cooperation on behalf of Captain Lasky. While understanding of Spartan Locke's intentions, he was understandably distrustful of the human standing before him, not only because of the ONI logo on his armor, but he somehow recognized him as the very [former] agent who volunteered to terminate him during the war. In response, Locke sternly-yet-politely pointed out that he saved his life. And 'Vadam was even more concerned that he was hunting the very Spartan he fought alongside with six years ago, whom he referred to as the "greatest of [the Spartans'] clan". However, using her recently gained access to the Domain, Cortana suddenly blacked out every network at the camp, taunting Locke in the process. Halsey came up with a plan that involved locating a Forerunner Constructor at a support station for the Guardian and inputting commands into it to make the construct activate the Guardian for Osiris. And while the Swords of Sanghelios had the firepower to get the Spartan-IVs in Sunaion, he refused to commit to an attack on the final stronghold of Jul 'Mdama's Covenant until victory was a guaranteed certainty. He was briefing his fellow Swords at the camp who were alarmed by Cortana's disruption, reminding them they fight one enemy at a time; their target being 'Mdama's Covenant. While his Sangheili were alarmed by the Guardian's inevitable reawakening, he assured them that he was relying on it, stating that the Guardian's departure in the eyes of 'Mdama's Covenant who worship it and its makers will be further demoralized upon seeing their idol deity depart and abandon them to their fate at the hands of the Swords. ' At some point, from his security officer Mahlo 'Turagg (via an interrogation toward a Covenant Unggoy), Thel discovered that Murok 'Vadam, one of his own family, was the one who betrayed him and left him to die during 'Mdama's Covenant's attack at the Elder Council Chamber. Murok was cooperative during his interrogation, thinking the Arbiter wouldn't kill anyone from his own clan; he was soon proven wrong as Thel executed him for his treachery.

Jul 'Mdama's Covenant deployed a between the support station and Osiris' position. While the Arbiter's forces engaged the Kraken with air squadrons, Osiris provided ground support. While the Swords of Sanghelios pushed the Kraken into a retreat, Osiris boarded the walker and destroyed its power core. With the Kraken destroyed, Osiris entered the nearby Forerunner support station and retrieved the Constructor. However, the Spartans were suddenly engaged by Promethean constructs. After battling their way to the extraction point, Osiris returned to the Swords of Sanghelios camp at Nuusra, where 'Vadam and Spartan Palmer were discussing the aerial assault on Sunaion, and was ready to begin his attack and finally destroy 'Mdama's Covenant. As the Constructor departed to activate the Guardian, the Arbiter's forces launched their assault on Sunaion.

Battle of Sunaion
"Thel 'Vadam"

- Palmer



'Vadam's Swords of Sanghelios and Spartan-IV Fireteam Osiris traveled to Sunaion aboard a, narrowly avoiding anti-air weaponry. While the Arbiter led his forces in engaging Jul 'Mdama's Covenant forces, Osiris destroyed the anti-air emplacements to allow more air support from one of the Swords of Sanghelios' fleets. Osiris then moved towards the Guardian's position, with Locke warning the Arbiter to move his fleet before the Guardian set off its concussive blasts upon activation; 'Vadam responded with a Sangheili proverb about victory and honor, and personally asked Locke to send John-117 his greetings. However, while Swords and 'Mdama's Covenant were fighting each other in the upper levels, Promethean constructs appeared and began engaging both Sangheili factions near the Guardian's location, and eventually started to overwhelm the Arbiter's forces. As the Guardian began to initiate its activation sequence, parts of the city began falling apart. Osiris arrived at Arbiter 'Vadam's location just as he was killing a Promethean Knight, and he soon reacted with anger that Prometheans kept warping in. The Arbiter and the four Spartans came under continuous attack from Promethean forces and were soon attacked by the Warden Eternal. The five managed to defeat the Warden and his Prometheans, just as the Guardian began to leave Sanghelios. Palmer managed to pick up the Spartans in a Pelican and drop them off aboard the Guardian before the construct left the planet into slipspace. 'Vadam then regrouped with his own soldiers and led the Swords of Sanghelios in eliminating the last of 'Mdama's Covenant forces on the planet.

Meeting an old friend
"When we first met, we were enemies fighting to end each other. Now as allies, I am confident we can face this new threat together once more."

- Thel 'Vadam showing his respect and willingness to help the Master Chief through ongoing crisis.

After his victory at Sunaion, 'Vadam and his forces returned to their campsite at Nuusra with Halsey and Palmer. However, during this time, a Guardian returned back to Sanghelios after the Sangheili refused to surrender to the Created, a faction of rogue artificial intelligences founded by Cortana. The Guardian finished off the remaining Covenant ships and began blacking out the planet with ground assistance of Prometheans which were sent in to pacify cities that refused to surrender.

After escaping from Genesis, Fireteam Osiris and Blue Team returned to Sanghelios where John-117 and Thel were reunited for the first time since they fought together on Installation 08. The Chief introduced Blue Team to Thel, who proceeded to invite his old friend and the new arrivals to join in a celebratory meal commemorating their victory over the last of Jul 'Mdama's Covenant. Thel and the Master Chief subsequently spent part of the night reminiscing about their past. Also the Arbiter reassured the Chief in his support in the coming fight against the Created. The next day, the humans left the planet for a rendezvous with the near Suban, one of the moons of Sanghelios.

Mission to Netherop
In 2559, in the middle of the Created conflict, the Arbiter, accompanied by the Spartan IV Olympia Vale, lead a mission on the hostile world of Netherop in an attempt to locate a rumored ancient artifact which could be the key to ending the Created's rule over the galaxy.

Personality and traits
"I have had many names in this long war. The humans knew me as 'Destroyer'. In the Covenant, I was Supreme Commander. The Prophets named me... Arbiter. And your Master Chief calls me... friend."

- Thel 'Vadam on his life.

Thel, like most Sangheili, held an obsession with honor and tradition for most of his adult life. However, he was more flexible than his peers when it came to the tactics that he used, and in particular showed a keen interest in human weapons even before the Great Schism. His worldview changed greatly during the Great Schism. While once zealous and unquestioningly obedient to the Prophets' will, after learning of the true nature of the Halo rings, he became more open-minded and accepting of the humans, his former enemies. His experiences as Arbiter also made him more pragmatic than most Sangheili, being willing to accept help from the UNSC in fending off an assault on his keep. He has shown to be true to his title "Arbiter", and sometimes tries to negotiate with his enemies, such as Yanme'e during the Battle of Earth (though this fell on deaf ears).

As noted by Jameson Locke in his target profile on him, Thel was an incredibly brilliant commander, known for utilizing advanced tactics that made his fleet unstoppable. Among the Covenant, he was noted for being one of the youngest Sangheili to attain the ranks of both Shipmaster and Supreme Commander. During the war, 'Vadamee was known for his tendency to lead campaigns from the front lines. His unorthodox tactics in comparison to the Covenant at large quickly caught the eye of ONI; Lieutenant Commander Locke considered him the most dangerous asset the Covenant had due to his strategic unpredictability and tactical flexibility. After the Fall of Reach, 'Vadamee's influence within the Covenant fleet had grown so great Sesa 'Refumee suspected the Prophets may perceive him as a threat to their power even before learning of his appointment as Arbiter. Thel also managed to inspire great loyalty in his subordinates. While Rtas 'Vadum initially lost his respect for Thel for the loss of Installation 04, Thel's subsequent actions at the gas mine and Installation 05 restored it and strengthened their comraderie, to the point where Rtas spared Earth from a full Flood-quelling glassing at Thel's urging. Jora 'Konaree thought of him like a cousin, and Sesa 'Refumee considered him to be the only individual that he would trust with 343 Guilty Spark's revelations, though Thel's appointment as Arbiter prevented any detailed conversations. Even so, however, he was able to comprehend the same message when it was told to him by the Gravemind, John-117, and 343 Guilty Spark.

After the Battle of Installation 04, he was ashamed for his failure at Halo, and wished only to regain his honor before dying for the Prophets. He remained stubbornly attached to his faith even after the betrayal of Tartarus and his encounter with the Gravemind. However, when he heard the truth of the Sacred Rings from 343 Guilty Spark, he finally accepted the truth surrounding the Great Journey. Following his betrayal by the Prophets, Thel developed an intense hatred of San'Shyuum and Jiralhanae. Despite this, Thel was gracious enough to attempt to reason with the Jiralhanae Chieftain Tartarus in Installation 05's Control Room.

Despite his former hatred for humans, Thel has displayed great respect for some, even former battlefield foes. He also holds admiration for humanity's courage; this is most clearly seen by his actions to avoid the glassing of Earth, even though that meant risking a possible Flood outbreak. Presumably due to the role Johnson played in his killing of Tartarus, Thel respected him greatly and grieved his death, expressing sorrow to the Master Chief, but promising that his sacrifice would not be in vain. Despite initially hating the Master Chief greatly for destroying Installation 04 and being the "Demon" of the Covenant who killed so many soldiers, the Arbiter came to greatly respect and trust the Chief. The Chief and Gravemind helped convince him of the truth of the Great Journey and they fought together against the Covenant and Truth. Together they defeated Truth and deactivated the Halo Array. When the Master Chief went to rescue Cortana and activate Installation 08, Thel remained behind to help him and shared a nod of respect with him when it was over. Even though the Master Chief was believed to be dead, Thel showed disbelief in this presumption, confident that the Spartan had survived thanks to his extraordinary ability to overcome impossible odds. After the events of Ealen IV and discovering the Chief was still alive, Thel believed John was the key to the galaxy's future. He also admitted to Spartan Locke that even when they were enemies and he called the Chief "Demon," it was with a modicum of respect for him. He also admitted that after their alliance he came to see the Chief as an ally as well as his friend. Before Fireteam Osiris entered the Guardian on Sunaion to find the Master Chief, the Arbiter complimented Locke with a Sangheili proverb, and then asked Locke to send the Chief his greetings. Olympia Vale remarked that she had never heard an Elite address a human in such a way. After reuniting with the Chief, Thel warmly greeted him and the two spent part of the night catching up on old times. Before they parted ways again, Thel expressed confidence that together as allies they could defeat this new threat.

Equipment
During his military career in the Covenant as Supreme Commander, Thel wore a golden Gheocin-pattern combat harness. After falling in disgrace and be appointed Arbiter he started wearing the traditional Arbiter armor. While 'Vadamee continued donning the traditional Arbiter armor after the war, he has more recently started wearing a custom-built ceremonial battle armor intended to pay homage to past Arbiters and symbolize his newfound role as a leader of his people. This armor is gold-colored and more baroque than his old Arbiter armor. He favors the energy sword, occasionally wielding his personal sword known as the Prophets' Bane. Thel most often uses the and  in ranged combat.

Production notes
Voiced by Keith David, the Arbiter was introduced as a secondary playable character in Halo 2; this was part of Bungie's creative decision to broaden the scope of the story from what Jaime Griesemer referred to as an "alien war movie with a space marine". According to Joseph Staten, the character's genesis was heavily tied to the idea of creating a figure who suffered the consequences of the Master Chief's success in Halo: Combat Evolved. Reception to his inclusion was mixed; Bungie community lead Brian Jarrard attributed some of the fan backlash to a discord between the game's marketing and the actual gameplay; whereas the marketing presented the game's focus as being the defense of Earth from the Covenant, this aspect constitutes only the first missions of the game. In Halo 3, the Arbiter was relegated into a supporting character and there are no levels designed solely from his perspective; he remains a playable character in the co-op campaign.

The original title for the character was "the Dervish", a title from the Sufi sect of Islam, but was changed to avoid overt parallels with the Muslim world. Ultimately, it was decided that "Arbiter" was more thematically suitable for his character arc. In the Spanish versions of Halo 2 and Halo 3, the Arbiter is translated as Inquisidor, which means Inquisitor. This is because the cognate of Arbiter in Spanish, "árbitro", means "referee".

The name Thel 'Vadam was established in the novel Halo: The Cole Protocol; in all preceding media, the character is only addressed by his titles. While the narrative does not explicitly connect the character with the Arbiter introduced in Halo 2, his assignment to the Fleet of Particular Justice is referenced near the end of the novel. Much later, Halo Waypoint confirmed that Thel 'Vadamee was indeed the future Arbiter.

The Arbiter wears mandible guards in Halo 3 despite lacking them in Halo 2 and Halo 2: Anniversary. Halo: Escalation depicts 'Vadam in the likeness of Halo 4 ' s Elites, most notably through the light tone and sparse texture of his skin. Halo 2: Anniversary ignores this overhaul, though he does wear his armor from the comic series in the "bookend" cutscenes—albeit with an open helmet with fixed mandible guards. Halo 5: Guardians ' depicts 'Vadam in the likeness of Halo 4 ' s Elites like in Halo: Escalation, though he continues to wear his armor from the Halo 2: Anniversary "bookend" cutscenes, though it no longer sports the open helmet. This is due to resource management rather than a retcon.

Trivia

 * When the Arbiter activates his active camouflage in Halo 2, his eyes will remain visible. This is visible only on Co-Op.
 * He is one of the few Sangheili to refer to John-117 as "Spartan". Even during and after the Great Schism, many still refer to him as the Demon (though some, notably, adopt 343 Guilty Spark's designation for him - Reclaimer). Rtas 'Vadum also holds this distinction. Thel has also called him the Master Chief.
 * In Halo 3, if the player outdistances or removes 'Vadam from the map (such as pushing him off a cliff), he will suddenly reappear as if phasing out of Active Camo. This also happens when the Master Chief enters the driver's seat of the Warthog at the end of the level Halo; the Arbiter will appear on the Warthog's turret in this same manner.
 * In Halo: Reach, an Unggoy may say in his native language something like "thalvadamee", though if it really refers to 'Vadam is unknown, as much of Covenant voice clips are simply reverse-English.

List of appearances

 * Halo: The Flood
 * Adjunct
 * Halo: First Strike
 * Halo 2
 * Halo Graphic Novel
 * The Last Voyage of the Infinite Succor
 * Halo 3
 * Halo: The Cole Protocol
 * Halo Wars
 * Halo: Reach
 * Halo Legends
 * Origins
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * The Return
 * Wages of Sin
 * From the Office of Dr. William Arthur Iqbal
 * Halo: Glasslands
 * Halo: The Thursday War


 * Halo: Escalation
 * Halo: Mortal Dictata
 * Halo: Broken Circle
 * Halo 2: Anniversary
 * Terminals
 * Halo: New Blood
 * Halo: Hunters in the Dark
 * Halo: Fleet Battles
 * Halo 5: Guardians
 * Limited Edition dossiers
 * Halo: Shadow of Intent
 * Halo Mythos
 * Halo Fractures
 * Lessons Learned
 * Halo: Tales from Slipspace
 * Halo Wars 2
 * Halo: Envoy
 * Halo: Legacy of Onyx
 * Halo: Bad Blood
 * Halo: Shadows of Reach
 * Sacrifice
 * Halo Infinite
 * Halo: Outcasts