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.
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. However, she has projected herself with taller forms in the past, such as in Halo 4 and the most recent Halo Infinite. Being a formless AI, Cortana can project herself as whatever shape or size she wants, choosing to model herself as a younger version of Halsey. Furthermore, her decision to be the same size as her human companions in the Halo show makes a certain amount of sense.
For starters, it's a bit of visual storytelling that establishes how Cortana sees herself. Right off the bat in Halo episode 3, Cortana views herself as an equal partner to John-117 while Master Chief sees her as a simple tool and upgrade he'd prefer not to have at all. If the games' canon is any indication, that will likely change over time. Furthermore, Cortana being human-sized is a strong visual cue that she's far more than a simple program. While Cortana may be under the orders of Halsey at the moment, her partnership with the Chief will likely turn into just as strong a bond as it does in the games and novels.
While some viewers may find the changes to Cortana's form and height strange, it's possible she may take on smaller projections when John-117 is in the field. Regardless, the canon of past games and books have established that Cortana's appearance is all about her own preference, a concept that seems to have been translated to Paramount's Halo series in some new ways when compared to the games. The TV series is already establishing that she's her own character rather than being a simple upgrade for John-117, and it will be interesting to see how she develops as the series continues.
Halo releases new episodes every Thursday on Paramount+.