When Sam comes in, Dean is asleep on the couch, head tipped back and a thin volume on Latin incantations resting open in his lap.
Sam huffs out a fond, breathy laugh through his nose and just stands in the doorway for a second, watching him. He loves Dean like this. Even in his sleep, the elder Winchester generally doesn't let go of the lines of worry that paint his face into a mask of intensity and focus far too solemn for his years. When he does, it's almost like a gift to Sam. Maybe he'll actually get some decent rest today, or Maybe he isn't dreaming about hell for once, even though he'd never in a million years admit that he still does, or Maybe if I sit down beside him and hold him, he'll just let me.
Which is exactly what Sam does. Cautiously and as quietly as he can, he makes his way over to his sleeping brother and sinks down next to him, making sure not to touch him until he's settled all the way in. Then, as carefully as if he's diffusing a bomb, he slips one arm over Dean's shoulders and dares to tug him in just a couple of inches closer, so that their heads are almost resting together.
Sam knows exactly how much hell he's gonna get for this when Dean wakes up (Are you trying to cuddle me, Sam? Did I grow a vagina overnight that I'm not aware of? Because unless that's the case, I'm not sure what got it into your head that I would let you cuddle me.) but he doesn't really care right now. Just wants to keep this for as long as he can.
As soon as he can't feel Sam's eyes on him anymore, Dean lets a small grin ghost over his lips and snuggles in just a little closer.