Instead, they decided on a brighter, expansive architecture and color scheme. Irrational designed the vertical and open-air spaces of Columbia to provide more opportunities to include various types of combat compared to the tight quarters of Rapture. 2K Marin assisted in building out the architecture and details of Columbia, given the much larger scope of the levels than previous BioShock games. While the floating city setting was developed early, the name "Columbia" and the thematic ideas of American exceptionalism that would inspire the story did not come about until eight months before the game's reveal. The game also incorporated influences from more recent events at the time such as the Occupy movement in 2011, which in spired how the Vox Populi group would grow from its haphazard beginnings. Levine reflected that despite the game's earlier setting, many of the modern day political turmoil calls back to similar tactics and behavior used in the early days of America's democracy, and thus provided a means to flesh out these aspects within the game. Central to the game is the relationship between the player character, Booker, and the AI companion, Elizabeth. Unlike BioShocks Jack and BioShock 2s Subject Delta, both of whom are silent protagonists, BioShock Infinites protagonist, Booker, was given his own voice and identity. Elizabeth, a crucial element of the game, was designed as a character which could not only be a useful AI companion to the player but a real partner with a significant emotional bond as well. The voice actors for Booker and Elizabeth—Troy Baker and Courtnee Draper, respectively—helped refine the story and their characters. Levine did not provide the actors with full knowledge of the story in order to help them develop their characters' relationship in a more natural manner. In the early development of Infinite, Elizabeth was designed to be more of a useful tool than a partner; she would perform tasks like picking locks that the player could not, but otherwise was not a major part of the experience. After Irrational saw players react favorably to Elizabeth in the E3 2011 demo, they expanded her role and abilities to make her a bigger part of the game. The approach to Elizabeth was inspired by the character Alyx Vance from Half-Life 2 as well as Monkey and Trip in the game Enslaved: Odyssey to the West. Irrational wanted to avoid giving Elizabeth any of the same tools