Most nights Sam will lay awake in bed for hours. Dean will have gone out drinking, stayed there for hours on end, longer than Sam thinks the bars are even open unless they're in a big city, and he realizes that he doesn't know where his brother is. The bar could have closed and Dean didn't come home. Maybe now he is walking around the town, maybe he is so drunk can't remember where they're staying. Or maybe he stopped in a convenience store and bought a bottle of Jack or Jim, maybe he found a place to drink it.
There are other possibilities, Sam knows, that will drive him crazy (well, crazier) with worry if he entertains them. Possibilities involving alcohol poisoning, random acts of violence, leviathans. Or even worse, possibilities he hasn't consciously acknowledged but he has sensed — a large ball of discomfort and anxiety settling in his stomach when Dean gets a certain look on his face, too focused, almost hypnotized, but restrained, as he cleans the guns or sharpens the knives. Rhythmic movements that make Sam tense as he watches, like he doesn't know what will happen next, even though he's seen them and performed them a million times before.
Sam presses his thumb into his palm, shakes these thoughts away before they form. There's some comfort in the fact that at least Dean isn't driving, but he doesn't understand why Dean won't just come home.
Sam stares at the door, at the ceiling, at the inside of his eyelids. He concentrates on the rhythm of his breathing, wishes they were in a motel. He misses the blinking of the standard motel clock, the clock that has always been a constant, the same everywhere they stay, black with red numbers, dots separating the hours and minutes, blinking to mark each second. He wishes he could focus on the passing of time — not on why his brother isn't back, or the flickering at the back of his mind that still doubts this reality, where the devil lies in wait. But these houses are perpetually still, nothing to focus on but dripping of rain, his breaths, his thoughts.
Some nights, Sam is still awake when Dean comes in. His eyes will have adjusted to the dark. He sees his brothers red rimmed eyes, how he walks as if he is not sure if there's ground below each step, heavily intoxicated. It makes Sam angry in a way he doesn't understand but has never been able to control, makes him think terrible thoughts like why can't he just get better? and why does he have to make this so hard? He's ashamed, because he knows it's not easy, it's nearly impossible, yet he can't stop a selfish part of him from blaming Dean for not being able to overcome it.
Usually, Dean will be blitzed enough to flop onto the nearest padded surface and pass out. Other times he will enter with a bottle of whiskey in hand, lie on the couch and keep downing it as Sam is finally able to let himself doze.
And some nights Dean will enter the room looking cold and desperate, but instead of heading for oblivion in his own bed he'll come to Sam's, slip underneath the blanket. He lets Dean climb in, still fully clothed and in some instances still booted, wrap his arms around his brother and bury his face in Sam's neck. He will smell like whiskey and smoke. Against his skin Sam will feel Dean's eyelashes flutter, feel the wetness of his eyes. He won't be crying so much as leaking, past the point where alcohol helps keep him from crying, from feeling, like it's supposed to and instead has the reverse effect. It takes away his ability to suppress those things — he is no longer drunk and comfortably numb, he's shitfaced and out of control, despairing. Dean's arm reaches across and rest on his brother's chest, in need of contact; Sam slips his own arm under Dean, grips his shoulders, pulls him close.
These nights, Sam doesn't say anything. He doesn't tell his brother, "it's okay, it will be okay," and he doesn't ask, "what's wrong?" He knows he's not supposed to, that's not why they're here. And when Sam pulls his brother closer, kisses him softly on his forehead, his temple, and then his lips, Dean doesn't pull away. He doesn't say "stop being such a girl, Sammy," or lie, "I'm fine." They lay there, silent, feeling each other's heart beat. Dean's breath shudders, puffs against Sam's neck. His tears keep escaping; they run down his nose and onto Sam's skin. Sam just runs his hand through his brother's hair, soothing, I'm here. Though he will attempt to resist it, eventually Sam drifts asleep, exhausted and able to relax now that he knows Dean is not in any immediate danger, neither attacked nor passed out in the middle of the road.
When Sam wakes up, Dean will already be out of bed and sitting at the table with twin cups of coffee. He's trying to sober up, Sam knows, no way those measly few of hours of sleep could be enough to purge the alcohol from his body after how massively loaded Dean was when he stumbled in. Despite their closeness the night before, nothing will have changed. Dean will start his same routine again until they find a hunt, and resume it immediately after.
Sam doesn't know how to help his brother. He can't just take Dean's whiskey away, and he can't change the way Dean's brain has worked against itself for so many years. And although he likes to think they will, he honestly doesn't know if things will ever get better. The one thing he does know, though, is that if nights like these are the only way Sam is allowed to give some sort of comfort, the only times he can help Dean feel a little less hopeless, he's going to hang on to them as best he can.