Among BioShock Infinite‘s most mysterious elements is Elizabeth, the woman our hero, Booker DeWitt, is sent to rescue. While Irrational Games have shed some light on Elizabeth’s character, they haven’t talked about her at length…until now.

In a new behind-the-scenes video for BioShock Infinite, the developer reveals what went into bringing Elizabeth to life, from her voice to her likeness to her back-story. Irrational fretted day and night over every detail regarding Elizabeth because not only is she a presumed important component to the story of Infinite, but she’s also player’s companion throughout the vast majority of the game.

And so, as Creative Director Ken Levine explains, it was important that Elizabeth “worked.” Bringing Elizabeth to life started first with casting Courtnee Draper as the voice of Elizabeth, who imbued the character with a wide range of emotions — emotions that are integral to the character’s development.

After securing Drapeer, Irrational secured the services of motion capture actress Heather Gordon to perform all of Elizabeth’s movements. For all intents and purposes, what players see Elizabeth do in the game, Heather did in a motion capture studio.

However, hearing the actresses talk about their roles is all well and good, but it pales in comparison to seeing their performances in action. Luckily, this video shows both Draper and Gordon at work in the Irrational studios, pouring out literal sweat in order to bring Elizabeth to life.

The video touches upon Elizabeth’s AI, specifically how she will react to a wide variety of players. For example, if she’s paired up with a version of Booker that wants to run straight through most of the game, Irrational have designed AI routines to accommodate that.

BioShock Infinite Elizabeth Behind the Scenes Trailer

And once both Heather Gordon and Courtnee Draper had completed their work on the game, it was up to Irrational to find an actress to use as inspiration for the design of Elizabeth in all the game’s marketing. As luck would have it one such cosplayer fell right in their lap, one Anna Moleva, who bares a striking resemblance to Elizabeth.

Using Moleva’s likeness, Irrational Games was able to develop all the various promotional materials for the game, from the box art to the brand new CG trailer.

But now it’s time to unleash Elizabeth on the world, so that gamers can see how these various pieces all come together. More importantly, players will get to see how Elizabeth and Booker’s story, and the world of Columbia, function as a piece of entertainment.

What are your hopes for Elizabeth as a side companion? Do you see her as the main character of the game?

BioShock Infinite releases March 26, 2013 for the PC, PS3, and Xbox 360.