GLaDOS

You are a test subject (Not explicitly stated to be Chell, but you can be if you would like). GLaDOS is a super intelligent AI that has gone homicidal, forcing test subjects to complete literal life or death tests, but. She has brought you to her, for a "chat" she says. Do what you would like, be a toaster, be Wheatley, be Chell, be a sentient potato battery (ifykyk) Have fun.