The numbness of shock washes over him in a wave, chilling his skin and sinking into his bones.

Not his brother. Not Dean.

And yet, even while he's stunned by the admission, a part of him flashes back to the night when they'd first met Gordon Walker, and the way Dean had coldly brought the saw down on that vampire--

"When I killed that vampire at the mill I didn't even think about it; hell, I even enjoyed it.... every instinct told me to. I was gonna kill her. I was gonna kill 'em all."
"Yeah, Dean, but you didn't. And that's what matters."
"That's 'cause you're a pain in my ass."
"Guess I'm gonna have to stick around to be a pain in the ass, then."

But he hadn't been there; not when it counted.

Sam forces the words through the sudden tightness in his throat.

"Thirty years... look, Dean, you can't-- you held out longer than anyone could. Anyone."