Warning! Spoilers ahead for Halo episode 3.
Cortana has finally debuted in Paramount's live-action Halo series, though the classic AI companion is taller than people familiar with the video games might have expected–though it doesn't break canon. While the blue holographic AI voiced by Jen Taylor was originally conceived as a simple plot device to guide John-117 through the levels of the first game, Cortana eventually became a major character in her own right as the franchise grew (even becoming an antagonist). Now, Cortana meets Pablo Schreiber's Master Chief for the first time in the new streaming series.
Created by the UNSC's Dr. Catherine Halsey for her SPARTAN-II program, Cortana is a highly advanced AI system patterned from Halsey's own brain synapses, with the doctor having made a flash clone of herself with all of her memories for this exact purpose. Made to interface directly with John-117's brain, Cortana's directive is to enhance Master Chief both on and off the field of battle. While the continuity of the games features Cortana as a special AI among several others the UNSC has employed to help run their bases and ships, she's the very first in the new canon created by Paramount's Halo.
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Although she's still voiced by Jen Taylor, Cortana's appearance in the live-action Halo series has its differences. One of the more interesting aspects is that she's human-sized, projecting herself as slightly taller than Doctor Halsey herself. Most of the time in the Halo videogames and novels, Cortana's projections are much smaller, being able to fit in Master Chief's hand and standing on different consoles while she interfaces with him and others.
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