Nothing.
It was all he had now. Blank walls, a hard mattress and two meals a day. Not even Sam was there. But it didn't intimidate him. It only pissed him off.
Nothing.
He'd said it like a threat, like it was something, after everything they'd been through, that would make him crumble.
Nothing was his weakness.
As a kid and even now, having nothing to do drove him up the wall. He had always needed something.
But nothing was an old companion of his regardless.
It was what he'd felt after the heartbreak of Sam leaving for Stanford. In the seconds after his father had died. In the ten years he'd spent in hell after enduring what would actually break him.
Nothing was his defense. His wall.
He'd lost so much, saved so many thankless people, endured so many unbearable trials. Nothing made it bearable.
The Mark of Cain had given him the calmness of nothing when it had turned him into a demon. No regret nor grief nor pain. He had felt -
Nothing.
Because Dean's worth, in his own mind, was nothing.
Dean was nothing.
So when this douchewad threatened to make him talk by doing nothing he showed him just that.
Nothing.
No trace of fear, no gasp of panic. His eyes were dead, his breath was steady.
Because the only thing separating him from Sam, from his everything, was just that.
Nothing.