Their first argument is about Star Trek, and it's completely ridiculous. Dean had been trying to convince Cas that Star Trek is better than any other sci-fi creation to grace this universe, and even though Cas has never watched it, he was still adamant that it isn't all that great. And Dean thought that it might actually be the end of their short-lived relationship; that they were going to break up because of a screaming match about whether Star Trek or Star Wars is better.

They don't though, obviously.

But it is weird for a while, both of them slightly embarrassed about how much the argument had escalated, and a little worried that they'd tipped their connection off-kilter because of it. Cas has noticed that Dean is being unusually grouchy with him; he doesn't come up behind Cas at his locker and press a kiss to the nape of his neck, or hold his hand under the desk in class anymore. So when Cas sends Dean a text asking him to come over ASAP, he assumes it's some kind of intervention wherein Cas will tell him to stop being such a baby and they'll both sulk and make up.

So Dean goes over to his house, noting the empty driveway and the unlocked door. Cas doesn't seem to be anywhere in sight, so he just lets himself in as he's done plenty of times before, and heads upstairs for Cas' bedroom. It's all routine and normal until he opens the door, and then it's anything but routine and normal.

Cas is waiting for Dean in the middle of his bed, and everything about it is inviting. His legs are crossed lazily; thighs still open and calling, and his hips are pushed out as he leans back on outstretched arms. But what Dean can't take his eyes off – what's really grabbing his attention – is what he's wearing. Black boxer-briefs and what is unmistakably, a blue Starfleet shirt.

"What's going on?" Dean asks; his throat suddenly dry as he stares at the way the fabric catches just above one of Cas' hipbones. Dean flexes his fingers at his sides, so desperate to reach out and touch, but too stunned to coordinate his muscles.

"I was kind of an asshole about this whole thing, and well, if it's important to you then it's important to me," Cas says, shrugging nonchalantly as though he isn't giving Dean the fastest hard-on he's ever had. Dean, however, is still frozen to the spot and unable to move, just staring with his mouth open. "Are you just going to stand there?"

Dean takes his jacket and shoes off before he climbs onto the bed, kneeling down in front of Cas. He waits for Cas to spread his legs wider, making room for him to slide between. He leans over Cas with his lips parted, stopping just a breath away from Cas' own mouth. Dean runs his thumb over the hem of Cas' shirt, committing the sensation of the fabric to memory as he kisses Cas softly, trying to get his wits about him.

"This is me making it up to you," Cas says quietly, his voice gravelly and slow already, going straight to Dean's dick. "I'll let you do anything."

This knocks Dean into motion and he's pushing forward to crash his mouth against Cas', sparing little time before he works his tongue inside and goes to town. Dean can't help but groan at how pliant Cas is being, the way he just opens up and lets Dean lick at every inch; getting at his teeth and the roof of his mouth until he's fucking into it.

Cas makes all these little sounds in the back of his throat, whining and mewling as Dean bites at his lip too hard and licks over it each time, and it's a sound that Dean wishes he could replay in his head forever. He curls his fingers around Cas' wrists and pushes them out from beneath him, and they fall to the mattress with a bounce and a tangle of limbs.

Dean plans on taking his sweet time with Cas, so he ignores the hard line of his cock inside of his underwear, and instead moves to kiss his jaw, then his neck, then his collarbone. Dean's head spins when he pulls away to get a good look at Cas; his face flushed and lips slick and swollen, the blue shirt looking so vibrant against his pale skin, and Dean imagines the way it'll look against all the purple marks he plans on leaving.

Cas tries to push his hips up as Dean bites into the skin of his neck, breathing heavily as he leaves a clear path of markings, of quickly reddening bruises that begin from his jaw and disappear just beneath the collar of the shirt. Dean knows how much Cas wants to be touched, how much he wants to touch Dean as well, can feel his hands squirming beneath his grip, but Dean just takes Cas' wrists into one hand and pushes them further above his head. Cas' back arches with it and Dean rucks up his shirt until it's bunched up at his armpits, and he watches the way Cas' skin stretches over his ribcage.

"Fuck, baby, you look so good like this," Dean breathes, and he takes a moment just to watch Cas beneath him, looking up with half-lidded eyes and a heaving chest.

"Ah, fuck, I want you so much-" but Dean cuts Cas off by flicking his tongue out over his nipple, eliciting a shaky groan from him instead. Dean decides that if all their fights end up like this, he wants to do it a hell of lot more often. He wants time to stop so he can spend hours making Cas come undone, until he's sweaty and shivering and begging Dean to give him what he wants – what he needs. Dean scrapes his teeth over the pink nub, bites down lightly until Cas' breath hitches again, then sweeps his tongue over and around, swapping for a repeat on Cas' other nipple.

"Please, Dean, please." Cas' pupils have swallowed up the blue of his irises, and he sinks his teeth into his lip as Dean presses a kiss to the hollow of his throat. Dean sits up to yank his shirt off in a rush, then kicks his jeans away, and finally his underwear. He moves to kneel over Cas again, his cock bobbing against his stomach, and Dean watches Cas' eyes track its movement. Cas angles his hips up towards Dean again, but he knows how this goes, and he waits for Dean to make the next move.

Dean lightly drags his palm across the bulge of Cas' underwear, and notes the damp spot of precome with interest. There are so many things he wants to do, and Dean is thankful for both of them being insatiable teenagers that can get it up again after ten minutes, because he wants to do everything. He starts with leaning down and pressing his lips against that same damp spot, and he feels the twitch of Cas' cock against his mouth, uses all of his self restraint not to suck him down there and then. Instead, he mouths at Cas' cock over the fabric, his tongue licking a stripe down the entire length. Cas' thighs are trembling around him, but he doesn't reach out to push Dean's head down, he just lies there obediently with his arms behind his head.

Dean pulls Cas' underwear off and moves back up his body again, letting Cas wrap his legs around his waist as he lowers himself down slowly.

"Don't be a tease," Cas grumbles, and he jerks Dean down with a dig of his heels, sighing when their cocks are pressed against each other. Dean gives him a bite on the chin in return, and a particularly hard thrust of his hips to wipe the smug smile clean of Cas' face.

"You just wait sweetheart, I'll make you feel fucking incredible."

Cas' head falls back against the bed at the drawl of Dean's words, because he has a way of making even the filthiest things sound beautiful and velvety.

"Maybe I'll even fuck you later."

Cas shudders beneath him and rolls his hips up, mouth falling open at the long-awaited feeling of their bodies moving together. Dean grinds into him, hands holding onto his sides tightly. They both know he'll leave impressions of his fingertips in the form of bruises, and Cas will poke at them with a fond pride tomorrow. Dean bites at the ridge of his collarbone again, sucks another stamp of possession there, then does the same to the juncture between shoulder and neck, and another just below his ear. All the while Cas is leaking precome like crazy, letting Dean rut into him hard and fast as the bed gives an ominous creak.

Dean loves the way Cas gets off on being pinned down by him, his lean body trapped beneath the solid weight of Dean's thighs and chest; no place to hide even if he wanted to. Cas' moans are coming at smaller intervals now, loud and uninhibited as he runs his hands through his own hair, squeezing his eyes shut. Dean knows what means, but he's not quite ready, not yet.

"Dean, Dean, I'm so close," Cas stutters, and his eyebrows are pulling together as he rocks up into Dean. And the flutter of his eyelashes and the sweat pooling in his clavicle is almost enough to tip Dean over – almost.

"Not yet, baby, not yet," and Dean licks a stripe up Cas' neck before nipping at his earlobe. "Be a good boy, hold on just a little while longer, yeah?"

And even though Cas is the very meaning of wrecked, he nods earnestly and takes a deep breath as Dean rolls his hips faster, a mixture of sweat and precome slicking their cocks now. He can feel his orgasm building from all the way in his toes, rising up through his body like a star on the verge of exploding, and he looks for Cas in all of this, wants nothing more than to see him go over the edge with him.

"Open your eyes – look at me, baby." The first time Cas tries to open his eyes, they go rolling back into his head, and it takes Dean fisting his hand in his hair roughly for Cas to keep them open the next time. But their stare is fixed and Cas comes right on cue – spilling out between their bodies as he shouts Dean's name and trembles. Dean tenses up watching him, his toes curling at the shape Cas' mouth makes around his name, and he paints Cas' chest in stripes of creamy white.

Dean collapses on top of Cas, slipping halfway off to sprawl across the bed as his breathing slows down. He looks over at Cas, whose eyes are glazed over as he looks at the mess they've made on his front, somehow avoiding the Star Fleet shirt that's still pushed up around his arms. Dean drags a couple of fingers through the come and brings it to Cas' mouth, letting them hover above his lips as come drips down onto his chin before slipping them all the way inside. Cas sucks them in and licks them clean with a sated smile, his tongue darting out to swipe even between the webs of Dean's fingers.

"Fuck, Cas, you're unreal." Dean chuckles, because he's still not entirely sure how he could have landed himself such a perfect human being.

Cas catches Dean in a lazy kiss, all slow-moving tongues and small smiles, the taste of both of them moving from Cas' mouth to Dean's. "If you fuck me into this bed I'll even watch Star Trek with you." And Cas' devious little grin is plenty of incentive for Dean.