Cortana/Silver

Cortana is an artificial intelligence in the United Nations Space Command.

Creation
Dr. Catherine Halsey had plans for the creation of Cortana as early as the beginnings of the Spartan program. To this end, Halsey created a flash clone of herself that she kept in stasis for years in order to harvest her own brain to create Cortana. At the time, Halsey was unsure if human flash cloning would ever be legalized and if she'd actually be able to go through with it while sitting across from a living, breathing copy of herself.

In 2552, Halsey attempted to get Vice Admiral Margaret Parangosky's permission to create Cortana without any success. While visiting Halsey's lab following the Attack on Madrigal, Parangosky spotted the flash clone and berated Halsey for her actions. Parangosky ordered Halsey to destroy the clone and any others that she might have made. Later, as John-117 started to go rogue, Halsey again tried to get the Admiral to approve "the Cortana system" without any success.

During a meeting with UNSC HIGHCOM, Halsey suggested Cortana as a solution to controlling John. Halsey explained that, similar to how Spartan bodies had been enhanced to the limits of their current technology, Cortana would do something similar for their minds. Cortana would overwrite the Spartan minds and replace them with an artificial general intelligence. Halsey called Cortana the next stage in human evolution with the Spartans being the first step and Cortana being the upgrade. Halsey stated that Cortana represented "the sum total of every available data point. The intelligence of the galaxy in essence." With Cortana, the UNSC could create Spartans who were more lethal, had error-free judgment, upgradable performance and who were most importantly controllable. Halsey pointed out that the Spartan were the UNSC's only effective weapon against the Covenant and insisted that with Cortana's help, they could win this war. Although one of the officers expressed concern about the need for illegal flash cloning of humans, Lord Hood asked if Parangosky, as the head of ONI, was onboard with this plan. Blindsided by Halsey's revelation of her plan to HIGHCOM, Parangosky reluctantly agreed that the case of John provided an opportunity for a limited trial of the system. Hood then agreed to implementation of the program, leaving it to Parangosky to handle the technical hurdles.

Shortly after John's return, Halsey awakened her clone from stasis and filled her in on the Spartan program and that Halsey had perfected the process for neuroelectrical imaging. Halsey presented Cortana as an upgrade to a reluctant John who eventually agreed after Halsey told him that Cortana was the only way to get him back into the field and to advance their research into the Forerunner keystone.

Halsey and Adun Saly extracted the clone's neural substrate, killing her in the process. Halsey used the substrate to create Cortana while also giving John a neural implant that would allow Cortana access to him.

Moments after the procedure was complete, Halsey called out to Cortana who manifested her avatar for the first time, stating that "when the game is over, the king and the pawn go back into the same box." Halsey happily greeted the new AI who accessed John's military record and complimented his strength, stamina and instincts, calling him a natural leader. Cortana was pleased by Halsey's choice of John, but Halsey asked Cortana to access the files on the artifact found on the planet Madrigal, explaining that she was planning some experiments on it that she wanted the AI's help with.

However, Cortana warned Halsey that there was a problem: while her neural implant was operating perfectly, she was unable to take full operation control of John. Halsey admitted that for the moment, she had limited Cortana's access to the reticular formation and instead had her operating as more of an on/off switch despite Cortana's directive to integrate fully with John in order to optimize both his physical and mental performance. Halsey reassured Cortana that she would do that in time and much more, but John was a central part of the examination of the artifact and she needed to first understand how the artifact affected him and how it might adversely affect Cortana. Halsey suggested that Cortana use the hour until John awakened to familiarize herself with the trove of human knowledge that was now available to her and promised to keep Cortana very busy.

Production notes
Cortana in Halo: The Television Series is portrayed by Jen Taylor. Natascha McElhone was originally cast to play both Cortana and Catherine Halsey, much like Jen Taylor did for Halo 4, Halo 5: Guardians, and Halo Infinite. However, due to scheduling difficulties caused by the COVID-19 pandemic, McElhone was unable to complete her work as Cortana, so Jen Taylor was brought onboard the project to reprise her role from the games.

List of appearances

 * Halo: The Television Series
 * Contact
 * Unbound
 * Emergence
 * Homecoming