[She draws in a deep breath slowly, holds it, and then lets it rush out. Claire knows why Felix is asking, why he should know and that she should have just said this in the first place.]

Sylar used to take people's abilities by slicing their heads open. He'd take it right from their brain, literally. So after he poked around in mine, not only did we discover that I can't die, but afterwards, I just stopped feeling pain. I don't know how or why because he never offered up an explanation. I don't think it was intentional.