It's the quiet sounds of frustration that wake him up.
It's still dark when Dean opens his eyes, the faint glow of the motel sign outside providing the smallest hint of light. He twists, groping for the alarm clock on the bedside table, groaning loudly when those blinking red letters proclaim it's only 5:30 in the morning and he's going to kill his brother.
But then he hears that sound again, tinged with a little desperation which has him dragging himself upright, rubbing the sleep from his eyes as he tries to focus on the shadowy outline of his brother.
"Sam?" he grunts, and the shape jerks minutely, distressed sounds silencing immediately in favour of hurried scuffling and a soft curse. Dean reaches across, flicks on the lamp and frowns at the sight before him.
Sam stares back for a half second before his head drops to his knees. Bare knees, jeans half dragged up the length of his legs. The plaid shirt on his torso hangs open, a pair of socks lie abandoned to the side and Sam's hand sit in his lap, stiff and curled like a claw.
"I couldn't sleep. Nightmare." Dean stays quiet. Sam has nightmares most nights. "Figured I'd, y'know, do something useful- but, I can't-" His hands are still held stiff in his lap, Sam sucking in a sharp breath. "Can't move my fuckin' hands, can't even fuckin' dress myself. I'm-" He cuts himself off, eyes averted and breath coming in heavy pants.
"It's okay," Dean blurts. What else is he supposed to say? Sorry your Hell memories fuck with you this bad? Sorry I'm a useless sack of shit who can't fix this?
"It's not okay, its not-"
"Sam." Dean slides out bed, dropping onto the mattress beside his brother. He reaches out, doing up the plaid shirt a button at a time. "It's okay. It's gonna be okay." It has to be. He doesn't want to see Sam suffer through the humility of being dressed by his brother like he was four years old again. And he can see how embarrassed Sam is, head dropped low, eyes hidden behind his hair as Dean help drag his jeans the rest of the way, muttering quiet assurances.
"You shouldn't have to do this," Sam spits, looking up with dangerously watery eyes, his jaw gritted tight.
"Shut up. You're my brother." He kneels down at Sam's feet, rolling on the cotton socks one by one, trying not to hear the soft hitching breaths above him. It's sheer impulse (and temporary madness, he insists later) that when he stands, he leans forward and kisses Sam on the forehead, looking down at the wide, damp eyes of his little brother.
And he'd do anything for him.