User:Halo-343/Draft2

"This galaxy is vast; its wonders and beauty are almost unfathomable. But the galaxy also hides dark secrets, some of which have lain dormant since the beginning of time itself.There is a danger in secrets, both in seeking and in knowing. Some things are meant to be hidden from view. Some mysteries defy understanding, and sometimes even the things we think we know are untrue. Some secrets should remain untouched."

- Cortana

Cortana, UNSC Artificial Intelligence serial number CTN 0452-9, is a "smart" A.I. construct, or "Intelligent Agent". She was one of the most important figures in the Human-Covenant War, and served as John-117's partner in various combat missions, as well as serving as the A.I. for the United Nations Space Command Pillar of Autumn and the Orbital Defense Platform Cairo Station. In addition, she held vital data pertaining to the Halos, including the Activation Index from Alpha Halo.

Creation
Cortana was created specifically for a SPARTAN-II mission to capture a Covenant ship, and kidnap a high-ranking member of the Covenant hierarchy. Cortana was to serve as the codebreaker, hacker and intelligence lead in the mission, and an exceptionally intelligent Human brain was needed to create the A.I. construct. It was decided that Dr. Catherine Elizabeth Halsey would the best possible brain donor. Under normal circumstances, the brain donor for an A.I. construct is dead, but Halsey's brain was flash cloned for the procedure. Twenty flash cloned brains were created, but only one survived; the survivor was used to create Cortana. The neural pathways of the cloned brain were scanned and copied through a process called Cognitive Impression Modeling. Her first words were "When the game is over, the king and pawn go into the same box" in Italian. She is one of at least two A.I.s that were created from Dr. Halsey's brain, the other being her predecessor, Kalmiya, another smart A.I.

The A.I. chose the name "Cortana" herself, and although Halsey did not tell Cortana that she had planted a viral termination code in her kernel, Halsey speculated that Cortana had already isolated and bypassed the code without her knowing. Cortana spend the first three years of her life residing in the computers of CASTLE Base, often accompanying Dr. Halsey in her work. Halsey enjoyed Cortana's presence, because she considered her an intellectual adversary, and also saw herself in Cortana; indeed Cortana is not only a facsimile of Dr. Halsey's mind, but also a replica of her physical form, albeit at a younger age. In Fall 2552, in preparation for the mission into Covenant-controlled space, Cortana was asked by Dr. Halsey to pick a "carrier". Cortana chose John-117 for their neural compatibility, although sharing Halsey's thoughts, considered him "attractive in a primitive animal sort of way".

Fragmentation and fateful meeting
On August 3rd, 2552, Dr. Halsey separated Cortana into two "fragments". One of these fragments, which contained all of her higher functions and personality, was stationed on board the UNSC Pillar of Autumn, while the other was tasked with mining data from the Forerunner artifact beneath SWORD Base.

On August 29th, 2552, the alternate fragment of Cortana was inserted into John-117's MJOLNIR Mark V armor for the first time, and the two then took part in a test to determine the strength of the armor's shielding systems. The test was devised by Colonel James Ackerson, a bitter rival of Dr. Halsey's who held secret contempt for the SPARTAN-II Program, and by extension, John-117. Ackerson incorporated armed ODSTs, anti-tank mines, automatic turrets in the razor field, and even a SkyHawk for an air strike into the test in an attempt to have John killed. Despite the obvious fact that the test was sabotaged, John-117 was determined to finish without breaking the rules. With Cortana's assistance, John managed to traverse the course relatively unharmed.

After the test, Cortana was installed into the as the primary AI, with another AI as backup. It was intended that she would be replaced with the Pillar of Autumn's true AI, but she was ultimately forced to take up this duty herself. While aboard, she exacted revenge upon Colonel Ackerson by hacking into his system and blackmailing him, hoping that this would send him back to the front lines. She also hacked into the SPARTAN-II highly classified personal files, and read over John's specifically. Cortana was horrified to discover the things Halsey had done to John and the other Spartans, and secretly vowed to protect him to the best of her ability. On August 30th, as the Autumn was making final preparations for the mission into Covenant space, Captain Jacob Keyes was informed that a massive Covenant fleet had dropped out of slipspace and were moving towards Reach. The Autumn was forced to abandon its original mission and assist in defending Reach.

Fall of Reach
During the closing stages of the battle, Dr. Halsey reunited with the surviving members of Noble Team, and tasked with delivering Cortana's fragment to the Pillar of Autumn, which had docked at the Aszod ship breaking yards, having chosen SPARTAN-B312 as her carrier. Although every member of Noble tasked with the delivery was killed in the process, Cortana was successfully brought to the ship, with Captain Keyes collecting the package personally. SPARTAN-B312 sacrificed refuge on the Autumn to cover their escape.

During the battle, Cortana excelled in her capabilities as an on-board A.I., managing to maneuver the Autumn through an asteroid field upon the appearance of a Covenant carrier, destroying the enemy vessel at the same time. Cortana also assisted Captain Keyes in destroying the Covenant supercruiser wrecking havoc upon the defending UNSC fleet. Despite these minor victories, the Covenant destroyed Reach's Orbital Defense Generators, and began glassing the planet. The Autumn was eventually forced to flee the burning planet, heading to a random location as per the Cole Protocol. However, Cortana secretly inserted coordinates translated from symbols on a rock that Master Chief discovered on Sigma Octanus IV, in addition to co-ordinates extracted from the Forerunner installation at the Babd Catha Ice Shelf beneath SWORD Base, believing them to be of significance to the Covenant.

Battle of Installation 04
The Autumn emerged from Slipspace in the Soell system, in orbit around the gas giant Threshold. It was there that the crew discovered Installation 04 in orbit around the gas giant. Even Cortana was clueless as to what exactly the ring was, only able to deduce that it was artificially created. However, Cortana then informed Captain Keyes that fifteen Covenant ships had pursued the Autum from Reach, and were moving to engage with boarding parties. Cortana took control of the Autumn and used what was left of its weaponry to destroy four of the fifteen attacking Covenant ships. By the time John-117 had thawed from cryo-sleep and reached the bridge, the cruiser was severely damaged, and Keyes was forced to initiate the Cole Protocol. He ordered Cortana to upload herself into John's armor so that he may protect the vital information she carried. John fought his way through the Autumn ' s service corridors with Cortana guiding him through, and the two escaped the ship in a lifeboat. The lifeboat entered the ring's atmosphere as the Autumn was shot down.

The lifeboat made a crash-landing on the surface of the ring, leaving John and Cortana as the only survivors. The two evaded Covenant patrols and rendezvoused with a group of Marines fending off a Covenant attack. Pelican Echo 419 dropped off a Warthog, and John and Cortana set out across the surface of the ring to rescue Marine survivors in the immediate area. At the same time, Cortana hacked into the Covenant Battle Network, and discovered Keyes' location - being held prisoner onboard the Truth and Reconciliation. The two were transported to the UNSC's base of operations on the ring, Alpha Base, and along with ODSTs of the Twenty-Second Tactical, devised a plan to rescue Keyes. John, Cortana and several Marines were dropped off near the Truth and Reconciliation that night and boarded the ship via its gravity lift. Cortana led John and his team through the innards of the alien vessel, opening doors and marking Navigation Points. The group eventually located Keyes and several other captured crewmen in the ship's brig, where Keyes told informed them that the ringworld was known as "Halo" to the Covenant, and that it actually operated as a weapon. The group escaped the ship, and soon learned that Halo's control room could be found using the Cartographer, a map room.

The next day, the Chief, Cortana and two squads of Marines set out for the island on which the Cartographer was located on. After fighting through significant Covenant resistance, the two reached the Cartographer, and found that Halo's control room could be found below the surface. As John and Cortana made their way back towards the surface, Captain Keyes informed them that he was going to investigate a supposed "weapons cache" with several other Marines. John and Cortana were retrieved by Echo 419, which descended into the innards of Halo towards the control room. The Pelican continued to descend as far as it could before dropping off John and Cortana on a platform. The two continued through a network Forerunner structures within a large underground chasm, with artificial weathering systems simulating a snowy environment, something that fascinated Cortana. After much fighting through much Covenant resistance, the Chief and Cortana reached Halo's control room, where Cortana was uploaded to Halo's core systems. Cortana was overwhelmed by the amount of data contained within Halo's systems, but discovered that the "weapons cache" Keyes and his Marines had gone after was nothing other than a Flood containment facility. Cortana urgently ordered John to rescue Captain Keyes before it was too late.

After the Chief encountered the parasitic Flood for the first time, he was convinced by the Forerunner Monitor 343 Guilty Spark to activate the Halo. During this time, Cortana absorbed as much data as she could from Halo's control systems. When John returned to the control room accompanied by the Monitor, he had recovered Halo's Activation Index, intent on using it to eliminate the Flood. John inserted the Index into the control systems, but was stopped by Cortana before it could take effect. Cortana absorbed all data from from the Index, and explained to John the true purpose of Halo; to wipe the galaxy clean of sentient life, which was the only way to truly eliminate the Flood. Guilty Spark confirmed this and summoned his Sentinels, demanding that Cortana be handed over. When John firmly refused, Spark left his Sentinels to eliminate them. The duo escaped the control room as the Flood began to run rampant across the ring, infecting human and Covenant alike. Cortana decided that they should overload Halo's three phase pulse generators to hasten the Monitor's activities. While the generators were disabled by John, Cortana discovered that the Pillar of Autumn was still structurally intact after its crash. She learned that overloading its fusion reactors would have enough power to destroy Halo, however Captain Keyes's CNI transponders would be needed to do so. Cortana tapped into the Monitor's teleportation network and transported both herself and John to where Keyes was known to be alive - the Truth and Reconciliation.

By the time John and Cortana arrived at the Truth and Reconciliation, it was already under attack from the Flood, and was severely damaged with a battle raging in and around it. Immediately upon arrival, the pair were contacted by Keyes, who weakly ordered them to leave him. After much fighting within the ship, Cortana observed that the Flood gathering bodies for use as biomass. As Covenant forces made a desperate push to retake the ship, the pair were once again contacted by Keyes who more firmly ordered them to pull out. Cortana was urgent to rescue Keyes at this stage, stating that Keyes was delirious. Eventually Keyes' transmissions had become agonized screaming. Finding the source of Keyes' transmissions on the ship's bridge, the two were met with a gruesome sight - Keyes had been infected and assimilated into a Proto-Gravemind. Cortana was horrified, but the two proceeded with their mission, and John retrieved Keyes' CNI transponders. The pair escaped the ship in a Banshee, and headed towards the crashed Pillar of Autumn.

John crashed the Banshee into the side of the Autumn, much to Cortana's irritation, and the two boarded the ship and fought through Flood and Covenant to the bridge. The Chief uploaded Cortana into the ship's systems, and she began a countdown timer to overload the ships reactors. However, the countdown was halted by none other than 343 Guilty Spark, who was on board the ship, and absorbing much of its data. Spark sent his Sentinels to capture Cortana and retrieve the Index. John suggested that they overload the reactors manually with grenades and rockets, to which Cortana reluctantly agreed. The two moved back through the ship, and reached Engineering, where they overloaded the Autumn ' s reactors. Cortana radioed Echo 419 to extract at an external access junction on the ship. As the Autumn began to explode and fall apart, John entered a Warthog and drove down a service corridor than ran the length of the war-torn ship. However, upon reaching their extraction point, Echo 419 was shot down. In an act of desperation, Cortana discovered a Longsword fighter still docked in Launch Bay 7. With little time left, the two entered the Longsword and sped away from Halo as it was ripped apart by the exploding Autumn. Upon scanning, Cortana found nothing but "dust and echoes", thinking them the only survivors of Halo, concluding that it was finished. John however, stated that they were just getting started.

Journey to Earth and Operation: FIRST STRIKE
For a short time after Halo's destruction, John sat quietly in the Longsword's cockpit, reflecting on what had just happened, and ordering Cortana to keep scanning for any at all survivors, or anything useful for their situation. Cortana was visibly irritated at these constant requests, pointing out that it would take eighteen days to scan the trillions of objects in the vicinity. However, after several minutes, Cortana did indeed discover something of interest - three cyro tubes that had been ejected from the Pillar of Autumn before it crashed. As Cortana moved the Longsword towards the cryo tubes, she discovered a Pelican dropship landed on an asteroid. Cortana dismissed the vehicle as crashed, but John noted its nose was in takeoff position. John retrieved the pods as seven Covenant ships entered Halo's debris field. The Longsword was sighted by two of the Covenant cruisers, which moved in to kill. The Pelican however, opened fire on the cruisers, distracting them, and giving Cortana time to accelerate the Longsword into the debris field, through the line of Covenant ships, and into a slingshot orbit around Threshold's moon, Basis. The two UNSC ships intercepted and locked onto each other, and they were met with the only other known survivors of Halo; Shiela Polaski, Locklear, Elias Haverson and Avery Johnson. John at first believed Johnson to be infected by the Flood, due to previous evidence during his encounter with them on Halo, however Johnson denied, stating the Flood "passed him up" and he escaped. Cortana pointed out that however unlikely that was, Johnson was completely fine medically. John quickly hatched a plan to capture the Covenant flagship leading the nearby formation, and using the Pelican as a decoy, Cortana hacked into the ship's systems and shut down its weapons long enough for the Longsword to make a crash-landing in its hanger bay.

Using the crashed Longsword's main cannons, Cortana cleared the hanger bay of hostile Covenant infantry, and John uploaded her to his armor as the group began to set out across the ship. After several skirmishes, with Cortana's advice, John uploaded Cortana into the ship's systems, to enable her to scan the ship for immediate threats and clear the way for John and his team as they made their way to the bridge. As Cortana explored the ship's systems, she encountered another presence which she believed to be a Covenant A.I. program, something not yet encountered by the UNSC. It was also during this period, that Cortana began to feel the burden of the vast amounts of data she had downloaded from Halo's systems, and began to show signs of slow processing and even exhibited uncharacteristic behavior including anger, distraction, and self-doubt, something John noticed. After John and the other survivors had managed to take control of the ship's bridge however, the rest of the Covenant ships in the battle group moved to engage the flagship, aware of its capture. Cortana, unable to jump to Slipspace, moved the ship into Threshold's atmosphere in an attempt to shelter from plasma fire as John journeyed to the engine room with a Huragok to fix the Slipspace drive. By the time the drive had been fixed, Cortana had plunged too far into Threshold's gravitational pull, unable to escape and unable to jump to Slipspace due to the atmospheric pressure. Despite Cortana's doubt, she attempted to make a slipspace jump regardless, and discovered that the Covenant's superior Slipspace technology enabled in-atmosphere jumps, and she promptly escaped. The group was split on where to take the ship, as going directly back to UNSC-controlled space would be a violation of the Cole Protocol. In the end, John convinced the others to bring the ship to Reach, to capture a reasonably intact UNSC ship in orbit, although his true motive was to confirm that his fellow Spartans had died when the planet was glassed.

The flagship exited from Slipspace in the Epsilon Eridani System eleven hours later, and the survivors found Reach almost completely glassed, with a Covenant occupation fleet still in orbit, clearing debris in the vacuum and deploying troops to a single undamaged portion of the planet. Cortana intercepted a UNSC E-band signal, and played it to the crew, all of which were confused with it except John, who recognized the transmitted tune as "Oly Oly Oxen Free", a secret Spartan call. John, as Cortana accurately predicted, convinced the others to descend to the planet and find the source of the transmission, knowing there to be living Spartans sending it. John and the others went down to the planet in a Spirit dropship, leaving Cortana alone on the flagship in orbit. During this time, after she isolated the name of the captured flagship, "Ascendant Justice", her communications routines were broken by the Covenant A.I., which proceeded to warn all Covenant ships in-system of the flagship's human capture. Cortana squelched the channel and stripped the A.I. code layer by code layer. However, thirteen Covenant warships moved to engage Ascendant Justice, prompting Cortana to test the improvements she had made to the flagship's plasma weaponry. The improvements excelled, and destroyed several of the enemy cruiser with single strikes. Cortana jumped out of the system, and emerged in the Oort Cloud, where she knew the Covenant would not find her.

Cortana used her time floating in the depths of the Oort Cloud to recharge the ship's plasma capacitors, eavesdrop on Covenant transmissions from Reach, and investigate the remaining code of the A.I. she had deleted. She discovered that the A.I. was full of errors and loops and constructed from poorly compiled code copies, and speculated that the A.I. was constructed from copies of human constructs. Using the base of the Covenant A.I.'s code, she managed to create a simplistic copy of herself to free some of her processing space. It was then that Cortana intercepted Covenant fleet order transmissions, and after checking three times, could not deny the destination of one particular fleet; Earth. Cortana made the short jump back to Reach, and minutes before she was to pick up John and his team, searched the wreckage in orbit for a ship with functioning reactors, and settled on the, attaching it to Ascendant Justice. Cortana made an extremely short Slipspace jump to the place in orbit where John, his team and survivors from Reach were being pursued by Covenant forces, allowing their dropship into the launch bay of Ascendant Justice. Cortana destroyed four of the three dozen attacking, and once again attempted to jump to Slipspace. However, just before the jump, she discovered that Reach's gravity had disappeared, which was impossible, and upon making the jump, Cortana found Ascendant Justice in a "space where there should have been no space at all". This odd "bubble" within Slipspace, limited Cortana's sensors to a mere one thousand kilometers, and fourteen Covenant cruisers followed her into the blue mist surrounding her.

Cortana was revealed to have taken a lot of data from Halo, and the sheer amount of information cut into her processing power and slowed her down. During her time on Ascendant Justice, Cortana exhibited uncharacteristic behavior including anger, distraction, and self-doubt - an indicator that she may have been about to enter rampancy. Dr. Halsey erased some data from her memory to give her more thinking space, including data regarding Sergeant Johnson's immunity to the Flood - a result of Boren's Syndrome.

It was also revealed that during Cortana's time on Ascendant Justice, she had captured a Covenant A.I., decompiling the A.I. and copying two of its functions: the ability to translate Covenant speech, and the ability to create imperfect clones of herself. These capabilities, along with her exclusive knowledge about the Halos, made her extremely valuable to the UNSC.

The Ascendant Justice was effectively fused with the UNSC Gettysburg. It was at this point that Cortana learned of a planned Covenant assault on Earth. The Master Chief, along with SPARTAN Blue Team and an expendable clone of Cortana (with all of the data the real Cortana had she was just too valuable to risk), would later execute Operation: FIRST STRIKE.

As it turned out, the Covenant A.I. that Cortana had decompiled had managed to, prior to its capture, send a message over Battlenet, warning the Covenant of its ship's capture and sending the necessary calculations for a sub-atmospheric Slipspace jump. The information was later used by the Prophet of Regret to enter Slipspace right above New Mombasa during the Battle of Mombasa.

Battle of Earth


After returning to Earth, Cortana was assigned to orbital defense platform Cairo Station, under the command of Lord Terrence Hood. On October 20th, 2552, John-117 and Avery Johnson were to be awarded the Colonial Cross for their actions on Installation 04, while Captain Keyes was to be awarded posthumously. At this time, the UNSC was on full alert, preparing for the inevitable Covenant attack on Earth, and the award ceremony was held on the bridge of the Cairo as a result. Throughout the hurried ceremony, Cortana informed Lord Hood of several Slipspace "whispers" detected near Io. As the ceremony neared its conclusion, Cortana sounded alarms across the station, alerting its personnel that a Covenant fleet had exited Slipspace just outside MAC range. Lord Hood gave Cortana command of the station's MAC gun, and ordered John to repel Covenant boarders.

After returning to Earth, Cortana served on the Orbital Defense Platform Cairo, where a ceremony for both Sgt. Johnson and Commander Miranda Keyes was soon interrupted by the arrival of a Covenant Fleet under the command of the High Prophet of Regret, starting the Battle of Earth. Cortana was given control of the Cairo's Magnetic Accelerator Cannon to repel the invaders, and with the Master Chief's help, she successfully deactivated a Covenant bomb that would have destroyed the station. She did this by uploading to the Master Chief's armor again for the first time since the capture of Ascendant Justice. When she did this, she somehow was able to do it through him merely touching the terminal her hologram was on, possibly an improvement as a result of Master Chief's new MARK VI armor. The same bomb was then used by Spartan-117 to destroy a Covenant Assault Carrier. The Chief offered for her to remain behind on the station after she said that his plan was crazy, but she chose to accompany him anyway. She then aided him when he arrived in New Mombasa to deal with a Scarab.

Delta Halo
Later, after escaping on-board the In Amber Clad in a Slipspace event, they discovered another ringworld, Delta Halo. Cortana gave Commander Miranda Keyes access to all information on the original Halo Ring, and provided intelligence to the Chief, UNSC Marines and the ODSTs on the surface of the ring.

After the Master Chief hunted down and killed the Prophet of Regret on Delta Halo, he, Cortana and The Arbiter were captured by the Flood central intelligence - the Gravemind. However, it did not harm them, instead choosing to use the two to stop the Prophet of Truth from firing the Halo. Gravemind sent the Master Chief and Cortana to the Covenant Capital Ship High Charity, where Cortana infiltrated the city's computer systems and remained there while the Master Chief followed the Prophet of Truth. She promised to detonate the crashed In Amber Clad's reactors to destroy the city and Halo if the ring was activated. However, she was left behind as a fail safe because she did not want to chance a remote detonation. As Truth boarded the Forerunner Dreadnought in the heart of the city to reach the Ark, Cortana fought with the ancient Forerunner A.I. Mendicant Bias to prevent the ship from launching without the Chief on board. The firing of Halo was averted by Miranda Keyes, the Arbiter, and Johnson, while the Chief successfully boarded the Dreadnought and escaped High Charity, leaving Cortana in the clutches of the true enemy, Gravemind, who had, by then, overran High Charity.

Captured
"Chief! High Charity, the Covenant's Holy City is on its way to Earth. With an army of Flood."

- Cortana's recording for the Chief.

Under the control of the Gravemind and constantly being tortured, Cortana managed to send a message to the Master Chief on Earth, stashing it on an Earth-bound Flood-infected ship that crash-landed in Voi. She succeded in doing this by creating a message and using the Gravemind's link to that ship to transmit it. The Gravemind allowed this and even helped it along in order to lure the Master Chief in, but was unaware of what the message said. In her message, she stated that the Gravemind was approaching Earth in High Charity, and that it was unaware of the portal generated by the Artifact and where it led to. On the other side, there was a solution to stop the Flood without needing to fire the remaining Halo rings; however, she couldn't give any further information, as the Gravemind might have been listening. Though Lord Hood doubted her plan, fearing it could be a Flood trap, the Chief stated that he trusts her. A joint UNSC-Covenant Separatist task force then entered the Portal, heading to Truth and to Cortana's solution. Ironically, Lord Hood was correct: the Gravemind deliberately let Cortana send the message to lure all of its enemies into one place, and then the Flood would overwhelm them all with the infested High Charity. It was also shown that some of her Cortana Moments were her defying the Gravemind and some were clones of her that she made to distract the Gravemind being consumed by him.

Cortana continued to appear to the Master Chief, who successfully recovered her from the Flood Hive that was High Charity after it crashed on the Ark. While the Chief reassured her, Cortana knew that she had taken irreparable damage in some places. Along the way, the Master Chief had several visions of her seemingly in pain. Surprised that the Chief had against all odds rescued her as he promised after the First Battle of High Charity, as well as being surprised that Chief and Thel 'Vadam (whom she encountered on Delta Halo with the Gravemind) "made nice", Cortana managed to gather herself and produce the Index from Installation 04, which she had kept. With it, Cortana was able to activate the newly constructed Installation 04, which fired prematurely, causing it to destroy itself and heavily damage the Ark in the process.

Stranded in Space
"But you did it. Truth and the Covenant...the Flood. It's finished."

- Cortana

The Slipspace portal collapsed as the Master Chief, Thel 'Vadam, and Cortana attempted to escape through it, cutting the UNSC Forward Unto Dawn in half. While 'Vadam, who was on the bridge, managed to return to Earth safely, the Chief and Cortana, who were in the hangar, were left drifting in space. Cortana activated a distress beacon, but knew that it could be years before they were found. As the Master Chief prepared to go into cryogenic sleep to await rescue, Cortana confessed to him that she would miss him.

Four years later after the portal collapse in 2552, the year 2556, she and the Chief are still stranded. Cortana, who is showing signs of Rampancy, tries to communicate with the Chief. As he is still in cryo sleep, she is unable to get a response from him. Cortana then begins to file a report on the history of the Forerunners and Humanity. After an unknown period of time, they are seen drifting towards an unidentified planet.

Personality


Cortana has a witty and playful personality and a small sense of cryptic humor laced with some sarcasm. She has neither arrogance nor false modesty about her immense capabilities, and her statements about her abilities have an objective perspective that human beings typically cannot achieve, but she does get bored often and easily. In fact, it is said that seven seconds of inactivity for an A.I. is excruciating. She has genuine, not merely programmed, loyalty to humanity and the UNSC, but exhibits devotion to John-117 beyond that which her programming or mission requires. She seems to be most loyal to him and is willing to help him with any task he requests of her. After she found out exactly what happened to the Master Chief as a child, she decided to protect him from further harm to the best of her abilities without compromising her mission. While a prisoner of the Gravemind, its her loyalty to him and trust that he will return for her that anchors her to sanity and allows her to hold on. Also, when she learns that the message she sent was allowed by the Gravemind as a trap she is horrified. Cortana also believes that she is the best qualified to watch out for John-117 and knows that he could get another AI to replace her, but believes that no one will ever look after him like she will.

Her personal loyalty is regarded as unwavering, but as an A.I. construct she is subject to corruption. Lord Hood questioned her reliability when it became clear that she had been compromised in some way by the Gravemind's possession of High Charity, on which she was trapped. John-117, however, never questioned her integrity. Cortana did consent to answer some of the Flood's questions, as a strategy for survival and the possibility of gaining information for the UNSC. Her sanity was pushed to the brink as she eluded the Gravemind's attempts to capture and dissect her for information. Her personal loyalty to and unwavering trust in John-117 helped anchor her and allow her to hold on despite being driven to the point of rampancy. Before she reunited with John-117 in Halo 3, she sent him a message, telling him about the Ark and warning him of the Flood-infested High Charity's approach to Earth. She was instrumental in finally putting a stop to the Flood at the end of the game.

She frequently jokes about having a relationship with the Master Chief and it is often implied that the two characters have developed some form of attachment. In Halo: The Fall of Reach, she says to Dr. Halsey that the Master Chief is "attractive in a primitive animal sort of way" while examining a photo of him. In Halo 3 his mere presence and reminder of his promise to her are enough for her to pull herself together to help him.

Rampancy
Cortana is also very aware of her short lifespan (a "Smart" A.I's lifespan is an average of seven years before rampancy) and her derivative nature as a copy of part of another person, rather than a true human being. Desperate and tortured aboard High Charity she murmurs: "A collection of lies; that's all I am! Stolen thoughts and memories!" Later on she says: "I'm just my mother's shadow..." and "It was the coin's fault," referring to the game of chance that Dr. Halsey played with John-117 when he was young. Halo: Evolutions Human Weakness reveals some of this to be her defying the Gravemind and a few of the more rampant things she says to be copies she made of herself which have been consumed by the Gravemind. She, along with Mendicant Bias, is one of only two known A.I.s that may have progressed completely through rampancy and became metastable.

However, this theory of metastability is disproved in Halo Legends short film Origins, in which four years after the events of Halo 3, it is strongly suggested that Cortana is falling into rampancy. She displays several characteristics to support this, such as her hologram flickering, trying to communicate with John-117 despite him being in cryo-sleep, recounting the history of the galaxy, which gets continuously more inaccurate to the point where events being recalled simply did not happen. She even tried to make physical contact with John via her avatar. Cortana's fate is left ambiguous, but it is assumed she became rampant.

Appearance
As Cortana is an AI, she has no physical body. She can communicate through comm systems and project a holographic image of herself from appropriate projectors, such as Holotanks. Her chosen avatar appears to be a nude female human (albeit censored by symbols over her body), roughly in her early twenties, with purplish/bluish skin, shoulder length purplish/bluish hair cut shorter at the back, and blue symbols scrolling down her body. In Halo: Fall of Reach, Cortana is said to resemble her creator, Dr. Catherine Halsey as a young woman, with a similar attitude "only unchecked by military and social protocol." When in a different emotional state, Cortana usually changes colors. This was especially noticeable in Halo: Combat Evolved, but less so in Halo 2 and Halo 3. Only in specific instances did she produce the color-changing effect. One instance of this was right before the Master Chief rescued her at the end of her eponymous level.

Bungie took a fair of amount of artistic freedom in the evolution of her appearance throughout the Halo trilogy, noticeably from Halo: Combat Evolved to Halo 2; she has longer hair, a more realistic humanoid figure, a much more feminine appearance and a slightly different shade of purple. In Halo 3, she becomes slightly bluer and again her face, hair, and body are changed to look more feminine and realistic.

Abilities
Cortana was designed to infiltrate computer systems and she is excellent at the task - she has become so intelligent that she understands Covenant technology far more than her makers and in some cases, the Covenant themselves. As of early 2553, she has never encountered a Covenant security measure that she wasn't able to bypass. In addition, she is proficient with UNSC military hardware and can run military ships and stations by herself. Indeed, the UNSC's primary use of AIs is to oversee targeting of point-defense weaponry used in space battles. For Cortana, this is merely an additional capability. She has helped out in several major battles including Operation: First Strike. She is capable of storing large amounts of data within her holographic appearance, hiding it in the microscopic lines of code that make up her visual form. Even when she is in the Data Crystal Chip, microscopic lines of code are running through the holographic "filling".

Cortana can be transferred among various computer systems. In Halo: Combat Evolved she needed a Data Crystal Chip to move in and out of various networks, including the Master Chief's MJOLNIR armor. In Halo 2, she merely needs to be touching another system to access it; however, this is most likely a product of the Master Chief's upgraded armor. Quite strangely, in Halo 3, she reverted to the data chip; this was probably because the Master Chief's armor was badly damaged during the fall to Earth that it reverted to a back up system, which also explains its different shield. However, there are some differences. Instead of having to be physically "plugged in" to the hologram projector, the Chief can just hold the chip close to it, at which point she "walks" off, later "touching" the chip to return to it -- holographic representations of the data transfer.

She is also very good at planning missions for the Chief, including the destruction of Halo. In Halo: The Flood the Chief comments that he's not sure who's better at blowing things up: him or her. It was also her plan that led to the destruction of all of the Flood that had escaped Installation 05 and saved the galaxy from a further Flood invasion. Apparently she has mission planning routines that help her with this as her clone told the Chief that that copy had only limited mission planning routines and was only able to help the Spartans form basic plans.

Another ability that she developed is a limited teleportation ability on Installation 04. She learned how to teleport on Halo while in its control systems, but as she couldn't access Halo's power grid, she couldn't perform this task very often. She did teleport once with the Master Chief by drawing power from his fusion pack saying that she was sure it wouldn't cause permanent damage to his power pack or shields, but both agreed that this should only be done once. She learned where they needed to go from the Covenant Battlenet and teleported them there although they ended up upside down due to her not getting the coordinates completely right. She has not used this ability since although she could presumably use it on any Halo but would have the same power requirements problem.

Another of her abilities is the ability to clone herself. She got this from a Covenant A.I. she destroyed and dissected. She first tested it by copying her language translation abilities and found it worked great. She also could seem to sense what progress the clone had made as if she retained a connection to it. Later, due to the importance of her getting to Earth due to all of the data she'd collected on Halo, the Flood and Covenant technology, she was forbidden from going on the Master Chief's mission, but she was able to make a clone of her infiltration abilities to give the Chief enough of her capabilities to infiltrate the Covenant command and control station. She claimed that this would not be a complete copy, but she thought that what it was would be enough. The clone had at least some of her personality as well. The clone retained her abilities to hack systems and some limited mission planning routines that allowed her to make basic plans to help the Spartans, but was unable to make the complicated plans that Cortana could come up with. The original clone made a copy of itself into the station's systems to help out and due to being overwhelmed by Covenant security A.I.'s, ended up making hundreds of copies of itself which overwhelmed the system and made accomplishing anything hard for the clones as they began to lose their coherent state, but still could control the system. The original clone was left behind in the reactor system. It was placed there to overload the reactors and never removed once it started the process. All of the clones created on the mission were destroyed when the station blew, but provided an invaluable help to the Spartan team. Later, while held captive by the Gravemind, Cortana used her cloning ability to create data-stripped clones of herself and ones of her lower-priority functions to distract the Gravemind. These were all consumed by the Gravemind, but they helped buy Cortana time and one also helped her create her message to the Master Chief. Some were even responsible for the more rampant parts of two of the Cortana Moments.

One of her other abilities is that she has the ability to control a variety of starships and stations and act as their AI even though that isn't her purpose. Cortana has acted as the AI of the Pillar of Autumn, Cairo Station, the Forward Unto Dawn, the Gettysburg and even the Covenant flagship Ascendant Justice. Despite it not being her purpose to act as a shipboard AI, Cortana is extremely good at it, with Captain Keyes being so pleased with her performance during the Fall of Reach, he ends up being glad he never got to initialize the Pillar of Autumn's true AI. During the time the Ascendant Justice was under human command, Cortana was able to control that ship easily once she destroyed the Covenant AI and was given full control of its systems by John-117. She proved even more adept at using the ship's technology than the Covenant were and was able to perform feats with it the Covenant never even thought of trying. While she was in control of that ship, Cortana is also able to act as the Gettysburg's AI at the same time, albeit while the ships are linked and is able to transfer herself from one ship to the other at will.

Trivia

 * Cortana is voiced by Jen Taylor, the same actress that voiced Princess Peach in several Mario games, Zoey from Left 4 Dead and Keira Stokes from F.E.A.R. 2: Project Origin. In Cortana's appearances in Halo Legends, she is voiced by Shelley Calene-Black. Black also voiced Catherine Halsey, reinforcing the connection between the two characters.
 * In Halo 3, look for a UNSC mobile computer. Watch the lower-left monitor. After a few seconds, Cortana's face will appear for an instant and then disappear. Two of the easiest ways to see this is to either look at the aforementioned screen in the beginning of Crow's Nest, or at one of the computers in the multiplayer map High Ground.
 * There was going to be an alternate story in Halo: Combat Evolved in which when Master Chief rediscovered Cortana inside the control room, she had become mad with power and wanted to take over Halo and the universe.
 * Originally, Cortana was supposed to have a British accent. This is evidenced by the fact that in Halo: Combat Evolved, Cortana uses several British idioms, such as "sod off!" when addressing 343 Guilty Spark.
 * She was rated as one of the ten most disturbingly sexual game characters by Games.net and one of the fifty greatest female video game characters ever by Tom's Games.
 * In Halo 3, she repeated lines Dr. Halsey has said before such as "You will be the protector of Earth and all her colonies." which Dr. Halsey says to the 6 year old Spartans in Halo: The Fall Of Reach. Cortana also recites a few lines from the Cortana Letters in Halo 3 in some of her messages and in the announcement trailer. Some of the lines are said in the Cortana moments in the level Cortana.
 * Cortana has been through 7 Notable Battles, again referring back to Bungie's love of the number.
 * It was noted by Dr. Catherine Halsey in the novel Halo: The Fall of Reach that at a certain angle, you could almost see a skeletal structure in Cortana.
 * Cortana has many similarities to the Marathon AI, Leela, such as control over certain functions of ships and other locations in their computer systems.
 * Being a smart AI, Cortana's operational life span is approximately seven years. However, after she took in all the Forerunner information in Halo's control room, her estimated life span was halved due to the vast task of storing, processing etc. all that information. In addition, this also noticeably decreased her efficiency, albeit temporarily.
 * The name Cortana (also Curtana or Courtain) is a latinised form of the Anglo-French curtein, from Latin curtus meaning "shortened." The name is used for a ceremonial type of sword; according to legend, one such weapon was the sword of Ogier the Dane; it bore the inscription "My name is Cortana, of the same steel and temper as Joyeuse and Durendal." Durendal (spelled 'Durandal' in this sense) was the name of an artificial intelligence in a previous Bungie game, Marathon. This also ties in with Cortana telling the Chief "I am your shield, I am your sword."
 * Strangely enough, although Cortana had worked with the Master Chief a number of times beforehand, Cortana seemed to have been unfamiliar with the Master Chief's armor systems when she was transferred from the Pillar of Autumn into John's MJOLNIR suit. However, due to her tone of voice, she may have been joking.
 * Cortana is the only one to call Master Chief by his real name in the Halo games, at the end of Halo 3.
 * The Chief seems to be unaware that Cortana is created from Dr. Halsey's cloned brain, although he can recognize that whoever died to create the A.I must be a genius, and that Cortana sounds more like a picky civilian than a military construct.
 * Her first words were, "Quando il gioco è finito, il re e il pedone andare nella stessa scatola." This phrase translates to "When the game is over, the king and the pawn go in the same box." It is unknown what would prompt her to say this, but one may suspect that she was attempting to convey that everyone is the same at death.