Mozie asked me for my more depraved version of 'who fell first' aka Dean being creepily obsessed with his little brother, so here is a little something something. Don't say I don't spoil y'all.
There's a tender age when there is little difference between a boy and a girl except what's between their legs, and it turns out that ain't exactly a deal breaker for Dean either. Go figure. Maybe it's just the raging hormones or maybe it's just curiosity, but Dean finds his eyes straying towards men as often as he does girls.
Sammy, who is small for his age, but so was Dean so he's got time, but for now Dean is acutely aware of how much bigger than Sam he is. He's always liked that about girls, how delicate they feel in his arms, under him, pressing up against him. Sam does that too, but it's not a fumbling teenage attempt at seduction, it's just artless innocence; he's still kind of cuddly, still likes being under Dean's arm on the couch, still fits so perfectly against him as his little spoon when he's had a nightmare. Dean isn't innocent about it like Sam is any more. Dean likes the way Sam feels against him, finds excuses to wrestle or just be close, to pin him, to overpower him, and he thrills at Sam's soft skin and bird bones. He likes to compare their differences: hands held up together, his dwarfing Sam's; the way his shirts hang off Sam's little body; the diminutive size of Sam's shadow as they walk together.
Sammy, who's in that androgynous stage of boyhood and is undeniably pretty. Dean gets called pretty boy all the time, but it must run in the family, because Sam makes his heart ache.
Sammy, who still has (and God willing always will) that starry-eyed hero worship for his big brother. It used to just make him proud, make him feel like hot shit, but now it makes his dick get hard when Sam looks up at him with sweet, big eyes and says 'woah, that was so cool!' when Dean does something like hit a bullseye from three hundred yards. He's gone from wanting to impress Sam because that's what big brothers do to wanting Sam's adoration because it makes him hard. He thinks about all the ways he could impress him with just how good he could make him feel, thinks about what it would be like to have Sam look at him like that when he's got him on his back underneath him and he's making him starry-eyed for an entirely different reason.
Sammy, who doesn't fucking realise how maddening the things he does are. His kitten pink tongue sticking out from his cherry blossom lips when he's focused on homework. The way he jumps up on Dean's back out of nowhere to demand a piggyback ride he's too old and almost too big for, wrapping his skinny legs and arms around Dean and laughing that tinkling, boyish laugh. The cute sounds he makes when he stretches, and God, there's something oddly erotic about that sliver of skin that gets exposed when his shirt lifts as he stretches his arms high, and Dean wants to lick it, wants to bite it.
So Dean is maybe a little obsessed and a lot fucked up, but he's not just some kind of pervert- okay, fine, maybe he is, but he loves Sam, too. God, does he love Sam. He fucking adores him. He would do anything for him, so it is any wonder he wants to be everything to him, too?
The wanting is overwhelming. He feels like he's going crazy. He starts being more tactile with Sam, touching him more often (in a mostly normal brother way) and Sam seems so happy by the change that he just goes further and further. More touches, more hugs, more more more. He kisses Sam's forehead and he scrunches up his nose like an adorable puppy and laughs, asking 'what was that for?'
He starts to wonder how far he can take it. How much can he get away with? When they sit on the couch together and Sam puts his legs in Dean's lap, Dean wraps a hand around one delicate ankle as if it's an absentminded gesture. He rubs his thumb into Sam's ankle. When he is lying on the couch and Sam tells him to make room, he just tugs him down and traps him in his arms, and Sam eventually relaxes. He relaxes so much that he falls asleep in the middle of the day, and Dean can't help but touch, hands roaming all over him, shivering at the softness of his skin.
With every pushed boundary there's a new one to demolish. Nothing ever satisfies him for long. Plausible deniability is his best friend. He wakes up with morning wood like any healthy boy and he has to share a bed with Sam, so he's gonna 'accidentally' end up grinding into his handspan ass a few (dozen) times, isn't he? A man can't be blamed for what he does in his sleep. Sam's a nervous, awkward little thing: he doesn't shove Dean away or make gross-out sounds or make fun of him. No, he just lies there as still and stiff as a corpse, heart racing and breath coming in fast as a hummingbird's wings, and he takes it. Dean doesn't push it at first, too scared to scare him off, but he gets bolder, needier. The first time he comes grinding into Sam's ass is the death knell for their relationship remaining wholesome.
He's so caught up in what he wants that it doesn't really cross his mind what Sam might want. Sure, he's considered that he's freaking Sam out, that he's gotta be delicate about this because he risks scaring Sam away and losing out on all the fun, but he doesn't consider that Sam might like it.
It's another early morning, another plausible deniability boner, and Sam's wearing one of Dean's shirts, so long it covers half his skinny thighs. It makes him mindless with lust. Carefully, he rucks it up so he can see Sam's ass, expecting his usual tight briefs, but what he sees takes his breath away.
Sam isn't wearing underwear.
Sam has never gone to bed without underwear on before.
He's still asleep. It's an invitation, right? It has to be. Oh God, please let it be.
Dean's hand fucking trembles as he pulls his cock free from his boxers and carefully, carefully, slots it into the valley of Sam's ass cheeks. Sam doesn't stir, doesn't go tell-tale stiff. Dean grinds into him, relishing the electric pulse of arousal, the softness of Sam's skin, the way his precum is slicking up the way. He loses himself in it, watching the obscene way they fit together, and fuck, they barely fit together, Sam is so small, Dean's dick looks even bigger in contrast to him, he's gonna-
"Dean," Sam moans breathily, and Dean comes all over that baby smooth flesh with a groan of Sam's name.
