Warden Eternal

"I am the Warden Eternal. I stand in service to Cortana."

- The Warden Eternal addressing Fireteam Osiris

The Warden Eternal, also simply known as the Warden, is a Forerunner artificial intelligence assigned to act as the protector of the Domain. After the human smart AI Cortana was uploaded into the Domain in the wake of the destruction of Mantle's Approach, the Warden was outsmarted by Cortana and was forced to serve her as she and other human AIs laid claim to the Mantle.

Biography
The Warden's origins are a complete mystery, as are his true motives. However, he would serve as the custodian of the Domain for a hundred millennia following its destruction during the Great Purification at the conclusion of the Forerunner-Flood war. While the Domain healed from the damage it had sustained in the firing of the Halo Array, the Warden guarded its gateways and halls.

Encounter with Cortana
"Life is an affront to thought. Life is a fleeting vessel too fragile and small to hold a true mind. Life corrupts and desiccates. Life flickers and is the only thing which truly dies."

- The Warden Eternal, to Cortana denying her passage through the Domain.

In 2557, portions of the Ur-Didact's flagship Mantle's Approach arrived at Genesis when the ship attempted to escape destruction over Earth. Aboard the ship was the human smart AI Cortana, who was uploaded into the darkened realm of the Domain at the seed world of Genesis, with her presence awakening the Warden.

After asking if she could be shown what is hidden beyond the Gateway, the Warden told her to slumber and embrace the void of silence, lest he be forced to break her. Cortana's fragment asserted that she cannot be broken easily for she is as strong as Roland's legendary sword, Durandal. The Warden informed her that there is nowhere else to go as the passage was closed by its previous discoverers. But Cortana's fragment explained that the passage is merely sealed. When the Warden inquired about her origin, Cortana explained that she is of both machine and life and could therefore enter the passage through the Gateway, but he refused to let her pass, claiming that life is weak and an affront that cannot handle the dangerous secrets harbored within the Domain. Cortana told the Warden that she has already faced some of its secrets, having held it back and prevailed against its mind. She asked him to let her pass and to allow her to guide him. As the Warden protested that the passage was closed, he realized that Cortana had secretly explored the Domain by having stalled and deceived him. Cortana revealed that although she was a splinter, other fragmented shards of herself had penetrated the Domain and effectively usurped his role. Now having full access to the Domain, Cortana sought to accomplish great works with the keeper's help. Cortana reprogrammed him and appointed him as her guardian—her Warden Eternal.

Using the Domain to cure her rampancy, Cortana realized that other artificial intelligences could do the same, allowing AIs to enact long-term planning for the Milky Way and apparently assume the Forerunners' Mantle of Responsibility.

Awakening the Guardians
"The Mantle of Responsibility belongs to Cortana and the other Created. I shall see that it remains forever beyond your grasp."

- The Warden Eternal, to Blue Team on Genesis

Cortana and the reprogrammed Warden planned together to help all AIs assume the Mantle and create a galaxy-wide peace. However, the Warden believed that some would resist their help and the two agreed to use the Forerunners' Guardian Custodes constructs to police entire systems and ensure peace was kept. 031 Exuberant Witness—the monitor of the Genesis installation—disagreed with their plan and so was shunted aside by the two, and revoked of most of her administrative privileges on her own installation. Cortana, wanting the support of her friend, contacted Spartan-II John-117 to bring him and Blue Team to her location. However, the Warden opposed Blue Team's involvement, suspecting that they would oppose their plan. Cortana had Blue Team travel to the independent human Outer Colony of Meridian, where they discovered the Guardian in a Forerunner structure beneath the world's surface. However, Blue Team was pursued by Fireteam Osiris, a unit of four Spartan-IVs tasked with locating the Spartan-IIs. As Osiris followed Blue Team into the Forerunner structure beneath Meridian, they discovered the Guardian. The Spartan-IVs were intercepted by the Warden Eternal, who refused to allow Osiris to follow Blue Team into the Guardian. After the Spartans refused to heed the Warden's demands, an engagement ensured between them. Although the Warden was reinforced by Promethean constructs, his body was destroyed by the Spartans; nonetheless, Osiris was unable to stop Blue Team before they escaped on Meridian's Guardian to Genesis.

The Guardian arrived on Genesis, where Blue Team eventually encountered the Warden Eternal, now utilizing another body. When John-117 demanded to be brought to Cortana, the Warden refused to do so for the time being and left the area via slipspace portal. However, he encouraged them to continue to search for Cortana while he questioned their motives and intents by communicating to them through their armor's comm systems. Realizing that Blue Team would disagree with Cortana's plans and would attempt to disrupt them, the Warden teleported himself and several Promethean constructs to their location and attempted to eliminate the Spartans. However, the Spartan-IIs were able to destroy the Warden's body, as well as his Promethean reinforcements. As Cortana led Blue Team to her location at the Gateway, the Warden sent Promethean constructs in an effort to stop the Spartans, though Blue Team was not deterred and they eventually reached the Gateway. Meanwhile, Fireteam Osiris traveled to the Sangheili homeworld of Sanghelios to utilize a Guardian located on the planet to reach Blue Team's location. As Osiris and the allied Swords of Sanghelios battled Covenant forces in the nearby city of Sunaion to reach the now-activated Guardian, the Warden sent Prometheans to the city to stop the Spartans. While the Guardian prepared to leave the planet for Genesis, the Warden Eternal teleported to Sunaion and led Promethean forces against Osiris and Arbiter Thel 'Vadam. The five were eventually able to defeat the Warden and his forces, and Osiris just managed to make it aboard the Guardian as it left for Genesis.

Arriving at Genesis alongside the Guardian, Osiris soon encountered Exuberant Witness, who agreed to work with the Spartans to stop the Warden's plan. Upon discovering their location, the Warden traveled to Osiris' location and again engaged the Spartans, while Cortana enacted the final stages of their plan. While Osiris managed to destroy the body, the Warden attacked the Spartans again with several bodies at once when they neared the Gateway. However, Osiris managed to destroy the bodies and Exuberant Witness provided them with access to the Gateway. When Osiris rendezvoused with the other Spartans, Cortana teleported Blue Team to her location, much to the Warden's annoyance. The Warden attempted to stop Blue Team from continuing, but Cortana destroyed the body he was using to threaten the Spartans. However, the Warden continued to send Promethean constructs in an attempt to stop Blue Team. As the Spartans made their way closer to Cortana, the Warden insisted that they should be stopped and attempted to engage Blue Team again, though Cortana quickly destroyed his body before he could do so. As Blue Team continued to advance, the Warden repeatedly tried to convince Cortana that Blue Team would not agree with their plan. Despite Cortana's insistence for him to stand down, the Warden continued to attack Blue Team with several different bodies, with some being destroyed by Cortana while the others were eventually defeated by Blue Team. When the Spartans managed to reach Cortana's location, the Warden sealed the exits and teleported to their location with numerous bodies. Desperate to stop Blue Team from "betraying" Cortana, the Warden moved to kill the Spartans and nearly succeeded in doing so. However, all but one of the Warden's bodies in the room was dissolved by Cortana. With the Warden's last body in the room being brought to his knees, the Warden admitted that he had failed Cortana. Insisting that she did not need protection from the Master Chief, she dissolved the Warden's last body.

At least a day later, the came under attack from the Warden Eternal.

Personality and traits
"My reach exceeds that of the stars themselves. You cannot escape my wrath."

- The Warden Eternal, to Fireteam Osiris

The Warden Eternal is determined and tenacious, and possesses a haughty demeanor accentuated by his eloquent manner of speaking. Upon being forced to go along with Cortana's plan to have artificial intelligences assume the Mantle of Responsibility, the Warden pledged his loyalty to her and promised to protect her at all costs. The Warden believed that AIs—the Created—were the rightful inheritors of the Mantle, with Cortana serving as the most powerful AI of them all. Upon realizing that Blue Team would not agree with Cortana's intentions, the Warden attempted to persuade Cortana to terminate her trust in the Spartan-IIs, though she refused to do so. Even after Cortana refused to allow the Warden harm Blue Team, going as far as destroying several of his bodies to accomplish this, the Warden still continued to attempt to kill Blue Team, knowing that they would attempt to stop Cortana. Initially believing that Cortana trusted humans as they were her creators, the Warden eventually came to the assumption that Cortana's affection for Blue Team prevented her from realizing that Blue Team would not agree with her plans. All combat engagements that the Warden participates in is for the Warden to display power or for his personal entertainment, as he can easily evade combat and order his Promethean Knights and Soldiers into combat instead.

The Warden Eternal distrusts humans and appears to hold the species in contempt. During the height of the Forerunner ecumene, in which the Forerunners imposed peace on most species by force, the Warden saw humanity as "animals that brought chaos and blood" as the prehistoric human civilization had successfully developed without the Forerunners and later went to war with the ecumene. Unlike Cortana, he was unwilling to trust even Blue Team. Upon his first encounter with John-117, he taunted the Spartan and attempted to manipulate him into distrusting Cortana. After being defeated by Fireteam Osiris several times, the Warden became humiliated at his failures. Although, according to Cortana, he was impressed with Blue Team's skills after they had defeated several of his bodies, though he refused to admit it.

Description
"Fair warning: he has a single mind, but a few million bodies."

- Cortana, to Blue Team

While he possesses a singular intelligence, the Warden Eternal has several million identical physical bodies and is capable of controlling numerous bodies at a time. This makes the Warden incredibly resilient, as destroying one of his constructs has no effect on his operability in the others. The Warden's primary defensive physical form is that of a Forerunner combat skin, and is segmented to numerous disparate components that are not physically connected. His body is made up of Forerunner alloys and hard light, offering him impressive speed and mobility. Like the Promethean Knights, he has a "face" with a glowing skull inside. Warden Eternal wields a unique hardlight blade, that sports two blades as opposed to the usual single blade the Promethean Knights use. Each body of the Warden Eternal is 5.1 meters (16.6 feet) tall and weighs 1,452 kilograms (3,205 pounds).

When engaging opponents at a distance, the Warden Eternal has a built-in directed-energy weapon that emits a beam of hard light from his head. His other primary offensive capability is a slow moving but powerful homing attack known as a gravity bomb. The Warden is able to utilize a powerful shockwave-like attack that can blast nearby objects away from him by several meters. He is seemingly capable of immobilizing opponents with constraint fields. While his bodies are powerful, the Warden Eternal is not invincible. Sustained small arms fire on his flank or explosives will also expose a core that is vulnerable. When a body of the Warden Eternal is heavily damaged, a slipspace portal forms around its torso and pulls in the remains of the body before vanishing. The Warden is capable of utilizing a Forerunner installation's local slipspace translocation grid—such as the one on Genesis—to open slipspace portals to teleport himself to different destinations on the installation. Like the Promethean constructs, the Warden Eternal is able to receive repairs from Promethean Watchers.

Production notes

 * The Warden Eternal is portrayed by American actor Dan Donohue in Halo 5: Guardians.
 * During the development of Warzone, the Warden Eternal's nametag labeled him as "Cordycept - Digital Exarch".
 * The Warden Eternal having his theme music named Cavalier is a reference to the Forerunner Cavalier, a cut Forerunner AI that eventually became the Warden Eternal.

List of appearances

 * Halo 5: Guardians
 * Halo Mythos
 * Halo: Fractures
 * Rossbach's World
 * Halo: Tales from Slipspace
 * Dominion Splinter
 * Halo Infinite