...I'd think they'd have to be aware of their roles, simply because that would run the risk of them unknowingly voting one of their own out, wouldn't it? I'd think they would want to avoid that.

[His tone isn't sharp, however; firm, but not harsh.]

But that does raise a valid point about how there must be incentive - after all, we weren't aware at the start that this little elimination game involved death, were we? So either they knew already and were all right with letting us die, or there's some reason they couldn't.