"You're tellin' me." Dean can't blame him. He's got a lot of guilt about leaving him behind, especially when he was having a better time of things. He stays quiet while his brother works it out in his head. He knows better than to interrupt him when he's trying to get a handle on things.

"Just that this place is crawlin' with monsters after sun down," he gives Sam an apologetic look. "The sirens usually warn you, but..." he trails off. It went without saying that if you got stuck outside you were screwed.