Cortana

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Cortana, UNSC Artificial intelligence (SN: CTN 0452-9), was a smart artificial intelligence construct. She was one of the most important figures in the Human-Covenant war, and was also John-117's partner in various combat missions as well as serving as the AI for the Halcyon-class light cruiser - UNSC Pillar of Autumn, Orbital Defense Platform - Cairo Station Charon-class light frigate - UNSC Forward Unto Dawn, and Stalwart-class light frigate UNSC In Amber Clad.

Personality[ ]

“Is this the secret you have kept from me? This... evolved ancilla?” — The Didact on Cortana

Cortana had a witty and playful personality and a small sense of cryptic humor laced with some sarcasm. She had 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. She did get bored often and easily. In fact, it is said that seven seconds of inactivity for an AI is excruciating.

Cortana seemed to share some of her creator's memories, thoughts, opinions, and even values. When she was asked by Dr. Halsey to pick a "carrier," Cortana chose John-117 for his neural compatibility and his "luck." A similar reason used by Halsey for her choice, too. She was not only a facsimile of Dr. Halsey's mind, but also a replica of her physical form, albeit at a younger age.

Relationships and Allegiances[ ]

Catherine Halsey[ ]

Dr. Halsey's and Cortana's relationship started off positive. Cortana assisted Halsey around CASTLE Base and even smiled at Halsey's presence. As rampancy took hold, Cortana began to distrust and become annoyed at Halsey. Cortana called her a "condescending bitch." Even after going to metastability, Cortana called her a monster for her actions in the SPARTAN-II Program.

John-117[ ]

She had exhibited extreme devotion to John-117 beyond that which her programming or mission required. She seemed to be most loyal to him and is willing to help him with any task he requested of her. After she found out exactly what happened to John-117 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, 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. Cortana also believed that she was best qualified to protect John-117 and knew he could get another AI to replace her, but believed that no one would ever look after him like she would. When John came into trouble by the Didact in the New Phoenix Incident, she told the Didact that she wasn't "...doing this for mankind." What was thought to be her final act, was protecting John.

She frequently joked about having a relationship with John-117 and it is often implied that the two characters have developed some form of attachment. Prior to Operation: RED FLAG, she says to Dr. Halsey that John-117 is "attractive in a primitive-animal sort of way" while examining a photo of him. During the Raid on High Charity, his mere presence and the reminder of his promise to her were enough for her to pull herself together and help him. During the New Phoenix Incident, she sacrificed herself to save John. One of the last things she does is touch him with a life-sized hologram, something she had always wanted to do. When John is devastated by her upcoming death, saying it's his job to look out for her, she tells him they are supposed to look out for each other and they did.

“I hate you! Cortana stop it! I have made up my mind! If I'm going to die aboard this ship, the Chief will suffer the same fate as me. Cortana stop! You sacrificed everything for him! Control yourself.” — Cortana, arguing to herself

While on board the Forward Unto Dawn, Cortana became increasingly conflicted about her feelings about John. At one moment, she down right hated him, back to her normal emotions. This conflict seemed to disappear once the Didact began to scan the ship.

The Warden Eternal noted Cortana's unusual devotion to John-117, warning her that it would be her downfall as he intended to "stop her reign before it even started". Even when John-117 told her to stand down and abandon her plans, Cortana was not angered, but simply disappointed in his decision. Rather then killing him and Blue Team, she decided to lock them inside a Cryptum to show him the error of his ways.

Humanity[ ]

Cortana used to have a positive view of humanity. Though she concedes to having her loyalties programmed in, she still feels as though she would be sympathetic to them without that programming. She even embraced some human values. However, as rampancy began to take its toll on Cortana, she began to focus heavily on humanity's constant war-like nature. This idea stuck with her, and became the main reason why she activated the Guardians in 2558.

Rampancy[ ]

“I need to think. Thinking is what's killing you!” — Cortana, arguing to herself

“I sense your malfunctioning companion. Human. And yet, she eludes me.” — The Didact on Cortana's Rampant state

Cortana was also very aware of her short lifespan (a Smart AI 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 to John: "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. Some of these outbursts are her defying the Gravemind and a few of the more rampant things she says are through copies she made of herself which have been consumed by the Gravemind.

Her rampancy only got worse as she was left to drift in the Forward Unto Dawn. 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.

Frank O'Connor confirmed that, "Seven years is the lifespan for a smart AI before it enters a state called rampancy. Cortana was getting close to the end of her natural lifespan at the end of Halo 3 but she has been exposed to far more information than any other AI in existence. She's going to develop some muscle from that process but it also contributes to her rampancy - that much information makes things worse."

When John and Cortana crashed on Requiem, she initially tried to hide it from him, Cortana was becoming rampant as it has been eight years since she came into existence. She believed, however, that it may have been possible for Doctor Halsey to repair her due to the way she was created. Throughout the game, Cortana's personality continued to fragment and this was used against her and John-117 by Captain Andrew Del Rio, though John-117 remained confident in her. Cortana was eventually able to take advantage of the fragmentation of her personality while on the Ur-Didact's Mantle's Approach.

Metastability[ ]

She, along with Mendicant Bias, is one of only two known AIs that may have progressed completely through rampancy and became metastable. After most of her was destroyed aboard the Mantle's Approach, the remaining fragments were sent to Genesis, curing her of her rampancy.