The thing is, sharing a bed with the newly fallen Castiel shouldn't have been awkward. They're grownups, they're long past the point of being strangers and most nights Dean's exhausted enough to sleep standing up anyway.
And for some reason it was always Dean who had to share thanks to his failure at rock, paper, scissors, Sam's insistence that he was bigger than Dean and needed more room, that he didn't know Castiel well, that Castiel didn't like him...
Basically Sam was a girl, so Dean wound up sharing motel beds with Castiel every time they stopped for sleep.
But the thing is...Unconscious Castiel? Kind of an asshole.
He hogs the covers, he somehow steals Dean's pillow in the middle of the night and coils himself around it, he's too warm, to the point it's like sleeping beside a furnace with a rapidly sprouting beard, he has nightmares and dreams that make him twitch in his sleep like a dog after rabbits, He doesn't so much snore are purr obnoxiously loudly, the one sleeping position he seems to know is 'The Starfish' and the one time Dean kicks him to make him shut the hell up, Castiel kicks back with enough force to make Dean limp all through the next day.
All without waking up.
He's also oblivious to all the things he does to interrupt Dean's sleep.
Sam knows that Dean is having trouble sharing with Cas, but the smug jerk is usually asleep and so doesn't grasp just how crazy Castiel can be once he's not conscious anymore. It's like after all that time just standing stiffly to attention he has to roll around and flip over as much as possible, limbs stretched out and flailing into a new position Every. Five. Goddamn. Seconds.
"Cas!" he elbows the slack form next to him, trying to shift him back to his own side of the bed. But Castiel has a kind of super limpness that effectively makes him a man shaped bag full of wet cement. Nothing doing. "C'mon Cas...please?" Castiel grumbles something into the pillow mashed under his face, swatting absently at Dean and pressing further into the mattress. Dean gives up.
He settles down to try and sleep. Castiel slips back into deep slumber and cranks up his creepy purring. It doesn't come in fits like snoring, just one continuous rumble of 'content sleeping bastard' noises.
Dean flops onto his back and tries to ignore it.
At some point he must sleep, he knows this because he has a weird dream that a monkey made of blankets is trying to kill him, which is something that has yet to happen to any hunter, ever, as far as he knows.
He wakes up with Castiel plastered against his side, one bare leg thrown over him, one arm around his waist and his face buried in Dean's chest. He's boiling hot as usual, the prickling hairs on his leg catching at Dean's own, sweat forming between their connected skin.
Dean will probably kill him for this. Castiel spazzing out is one thing, co-dependent limpet clinging is Sam territory and Dean'll be damned before he lets Castiel turn into Sam – one's more than enough.
Castiel sighs deeply and makes a sound almost like 'Mnf', right against Dean's nipple. Warm breath and the twitch of lip movement make him instantly uncomfortable and awake.
"Cas, whatever you're dreaming about, do that again and you're on the floor." He mutters, hoping to penetrate the dense wall the angel hides behind in sleep. Castiel doesn't move, but he doesn't move closer and that's all Dean cares about right now. He closes his eyes and tries to get back to sleep.
He doesn't so much sleep as black out, blinking one minute and losing three hours the next. He feels like it's been seconds, and for a moment the numbers glowing on the clock are so disorientating he notices nothing else.
That lasts for three, blissful seconds. But unfortunately he has to come to grips with his surroundings afterwards.
Castiel is moving in his sleep, but not his usual fitful twitches and flailing arms. His hips are rolling purposefully, rhythmically, against Dean's side. Dean can feel hardness pressing through the damp cotton of Cas's boxers, twitching against the curve of his hip. Dean squeezes his eyes shut and feels his heart thump once, hard.
Great, just great.
Dean's still lying on his back, Castiel stuck fast to his side, hips twitching against him. His mouth opens and hot air pours over Dean's nipple, hardened against the cotton of his shirt. Castiel's soft whimper goes straight to his half-formed midnight wood and Castiel moves more insistently, boxers sliding down a little with each rocking motion.
Dean prays, actually prays that this will end. That Castiel will stop, roll over and go back to being a wriggling starfish of annoyance. Anything that will put an end to the slow slide of cock against his hip, the pleading, almost lost sounds that catch in Castiel's throat as he grinds himself into Dean's flesh. His face presses against his chest, breathing rapid, and the soft cries form words, mumbling strings of please...please...oh...uh...ugh...God...please...mmmm...
Dean kind of snaps to attention at that. But no, Castiel is still asleep, just shuddering in frustration and pleasure and groaning his name.
And the elastic on Sam's cast off boxers apparently wasn't meant to withstand wriggling angels, the underwear slips down, and the feeling of damp cotton is replaced by too hot skin, wetness emanating from the tip of him and the silky catch of Castiel's uncut skin.
Castiel sounds like he could actually be in pain, squirming and huffing tight, frustrated whines as his so far untouched penis meets warm skin and prickling hairs. Dimly Dean realises that even this must be incredible for the guy, as far as Dean knows Castiel hasn't even touched himself yet.
Dean presses into the touch, he can't help it. Heat floods from the skin Castiel ruts against, to his own groin, pooling there and throbbing lazily. Castiel's breathing is shallow, roughening with every passing second, and he's so wet, pre-come pulsing and slip sliding between them, Castiel's cock a line of heat pressed into his hip.
Castiel's hand grasps Dean's hip as he rubs against him, fingers slowly sliding on sweaty skin until his hot palm is pressed into Dean's groin, friction where he needs it most. He's on the edge in seconds, Castiel writhing into his side, hand catching at his cock and...
...Dean wakes up.
"Dean?" Castiel's sleep blurred face squints at him from the blankets, hair flat and damp with sweat. Dean can feel their bodies pressed together under the sheets, one of Castiel's thighs pressed between his own. Wet heat is gathered at his crotch, still thrumming from an orgasm. Castiel's hand is on his arm, as if he was holding on to him, or just trying to wake him.
Heat flares over Dean's face.
"Shit...sorry..." He hisses, trying to pull himself together enough to get out of bed and clean up, embarrassment still burning through him. Castiel's hand slides down his arm, holding him still.
"I tried to wake you." He whispers, gently.
"I'm sorry, I was..." Exactly what he was Dean doesn't really want to contemplate.
"It's alright" Castiel's eyes are half lidded, sleepy and comfortable, not freaked out in the least. " 's natural." He half mutters, shifting and Dean can feel the press of Castiel's answering erection, urgent, against his thigh.
"Cas..." his voice cracks. Castiel's hand twines itself with his, guiding it underneath the blankets until it reaches his straining arousal.
"Please..." Dean can hear the wet parting of Castiel's lips, the rush of breath that comes with the word. Dean moves his hand, stroking slowly, and Castiel's head falls back against the pillow.
The thing is, needy Cas? Kind of irresistible.