At PAX 2011 today, Irrational Games and the two lead actors in BioShock: Infinite gave us another good look at what goes into the voice acting of parts in a virtual medium that has such a complicated story.
It't not enough to understand that your character has amazing powers that defy the laws of space and time. As these outtakes remind, there's also frightening confusion that attends such a gift, and a resentment of those who have even less understanding of it. To create those feelings, actor Troy Baker (Booker DeWitt) had to berate, out-of-script, his counterpart Courtnee Draper (Elizabeth), to the point of tears.
It's extreme but not unusual. When Kotaku's Kirk Hamilton spoke with Mass Effect 3 voice actor Jennifer Hale, she reflected on how much she enjoyed a similar process working in the same sound booth with David Hayter on Metal Gear Solid 4.
The clip above gives great insight into the character relationships that the two forged. The clip below shows how it comes together in a key sequence of the game.