Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/ works/626491. Rating: Explicit Archive Warning: Underage Category: M/M, Multi Fandom: Supernatural Relationship: Castiel/Dean_Winchester/Sam_Winchester Additional Tags: Underage_Sex, Underage_Drinking, Hot_Tub, Threesome_-_M/M/M, Sibling Incest, Step-siblings, Wincest_-_Freeform, weecestiel, Barebacking, Sloppy_Makeouts, Comeplay, ATM, Fingerfucking, First_Time, Anal_Sex, Top Dean, Bottom_Castiel, Top_Sam Series: Part 3 of Stepbrothers Stats: Published: 2013-01-06 Words: 9968 ****** Something Going on Beneath the Water ****** by saltandbyrne Summary “I wanna watch you,” Sam mumbles out, Dean's lower lip sucked in between his teeth with the last syllable. Dean was always more suggestible like this, pinned under Sam's wriggling weight and distracted by his mouth. While Sam's sure it would have happened eventually, he's not feeling particularly patient. And this will be good for Dean. (Sam is 12, Cas and Dean are 16). Notes This is all snappapple's fault - she asked for wet boys. You can blame her for this ginormous underage threesome PWP. :) I am ashamed to say that the title comes from Cee Lo Green's Hot_Tub of_Love. Dean's playing Halo when his phone buzzes.   Sam feels his heart skip at the dull vibration against the couch, watching Dean's face like a hawk as he slides his thumb across the screen and reads. There aren't too many options for what it could be, and Sam feels a tendril of conditional hope furl out into his stomach. Hopefully it'll be the message he's been waiting for, and much more importantly, Dean'll read it and react the way Sam wants.   The little twitch in Dean's jaw is familiar but unhelpful, not a tell yet because any interaction with their father brought out these tiny gestures of clenched fear and quickly-quelled disappointment. Only someone who'd spent his short life memorizing every inch and tick and freckle of Dean's body would even notice them.   Cas is stock-still on the big club chair across from them, eyes wide and fixed on Dean. He hasn't visibly moved, but Sam can see the taut lines of his body, tensed and ready to bolt at the first sign of one of Dean's black moods. Cas never handles conflict well, not that Sam could blame him. Sam only dealt with the fallout because he didn't know any other option.   It could go one of two ways, and Sam doesn't know for sure which one it is as Dean tosses his phone down and picks the controller back up. Sam swallows and picks a ragged fingernail against the microfiber of the couch, watching as Master Chief makes a swift execution before Dean goes back to the start screen.   “That was Dad.” Sam can see the reflection of the TV in Dean's eyes, flickering purple-white-blue across his impassive stare. “He's gonna be a few more days.” Sam can just make out the impression of Dean's tongue sliding over his teeth, pursing his upper lip out as he sucks lightly and leans his head back against the overstuffed arch of the sofa. Sam's lips curl up in a cautious smile at the hiss of air over Dean's teeth. That's it, Dean, let me help, make you feel better.   Cas isn't lacking in perception, just experience, so he's still cocked and ready like a ball of nervous energy. Sam shoots him a quick look, a soft wink and a reassuring smile as Dean blows a long breath out in between his lips.   “Know what I think?” Dean leans his head back up and looks at Sam and Cas in turn, nodding as his face draws into a slow, lazy grin. “I think we should use the hot tub.” Perfect.   “Cas, go turn it on. Hot.” Dean gives him a charming smile, all promise and sweet trouble until Cas is almost tripping over himself to get up out of the chair and head down the hall.   Sam watches him disappear with a series of anxious little skips before turning to Dean. His brother's smiling although it doesn't go all the way to his eyes, but that's OK. Sam knows how to fix it. Moving quickly, he slides himself into Dean's lap and kisses him before Dean has a chance to move.   Dean grunts in surprise but settles into it easily, sliding a hand up Sam's back as he opens his mouth and lets Sam do all the work. Sam swirls his tongue out to draw Dean's own into his mouth, prodding and teasing just to pull off when Dean finally moans softly and chases after him.   “I wanna watch you,” Sam mumbles out, Dean's lower lip sucked in between his teeth with the last syllable. Dean was always more suggestible like this, pinned under Sam's wriggling weight and distracted by his mouth. While Sam's sure it would have happened eventually, he's not feeling particularly patient. And this will be good for Dean.   “What?” Dean murmurs his confusion back into Sam's mouth, humming as he tries to pry Sam's lips apart with his tongue. Sam tilts his head back until Dean opens his eyes and looks at him.   “I wanna watch you fuck Cas.” Dean's eyes go wide as Sam trails his hand down his brother's chest, twirling his fingers in little patterns over the thin cotton of Dean's t-shirt. “I wanna see how you do it.” So you can do it to me.   Dean breathes out a soft exclamation and licks his lips. “Fuck, Sammy.” He squeezes his eyes closed and pulls Sam in closer, until Sam's smiling because he can feel Dean's cock, thick and familiar under his ass. Sam starts to move as soon as he feels it, rocking his hips in a slow, grinding figure-eight as Dean groans.   “You been thinkin' about that a lot, huh?” Dean's eyebrows are drawn together in that face he makes when he's about to say something stupid, like last year when he said Sam was too young to know what a blowjob was. Sam cuts him off with another kiss, rolling his tongue and his hips at the same time until he can feel the resistance drain out of Dean.   “Think about it all the time, Dean.” Sam latches his mouth onto Dean's ear, nipping and sucking at it as they both get hard. “Think about how big your dick is, how big it'll look in Cas' tight ass.” Sam feels a novel thrill at talking like this out in the living room, saying all the dirty things in his head out in the open air of their shared space where Cas could just walk by at any moment and all they'd do is pull him in and tug his pants down.   Dean's grunting in time with each dirty roll of Sam's hips, coming up to meet him now as Sam licks a stripe down his neck. “Want to see you come in his ass, Dean.”   “Jesus,” Dean huffs out against his ear, running both his hands into Sam's hair to pull him down for a deep, dirty kiss, moaning as he licks hungrily into Sam's mouth. This is the good kissing, where Dean isn't thinking about anything but spit and skin and Sam and Cas.   Dean's hands are firm and rough in his hair, and fuck if Sam doesn't want to just rub himself off right now, come in his shorts and squirm around on Dean's lap until he can do it again. But that's not the plan, at least not tonight, so Sam pulls back to the groaned displeasure of his brother.   “Come on,” Sam slips off his lap as quickly as he'd slid into it, tugging Dean up by the hand. “We can do it in the hot tub.” Dean bites his lip and digs the heel of his hand against his crotch as he stands up.   “Yeah, OK.” Dean takes a deep breath and smiles broadly. “Gotta get something first.”   ~~~   Cas is sitting on the edge of the hot tub when they get outside. Sam's got three beers clutched between his fingers and Dean's twirling the clear tube of “you'll see what it's for, pipsqueak,” in his hand. The only light is from the wavering blue-green spots in the pool, casting weird shadows on everything and glowing cool against Cas' pale skin as he perches on the edge.   Sam laughs a little when he sees that Cas is wearing his swimming suit, the bland khaki material clinging to his thighs as he swirls his feet in the hot, bubbling water. It's just like Cas, always so careful and unsure of himself. It would be irritating and nerdy in another kid, but with Cas it's just sweet.   Dean smirks, too, taking one look at Cas' shorts and stripping out of his clothes while Cas blinks and presses his lips together. He's too distracted to notice the little tube when Dean sets it down on the steps on his way in. Cas' eyes never leaving Dean's bobbing, half-hard cock until Dean sinks down into the water and stretches his arms out, sighing contentedly.   “C'mon, Cas,” Dean says smugly. “Get in.”   Cas pushes himself off his place on the ledge and gingerly sinks in, breathing out through the O of his lips as he adjusts to the heat. Dean liked it hot enough to boil them, so that's the way Cas made it.   Sam twists the caps off the beers and watches Cas watching Dean, reading the want written across his face like a neon sign. Sam is definitely not going to have to worry about talking Cas into anything.   Sam hands them each a beer and settles his own on the ledge before pulling his t-shirt over his head. Dean turns to look at him and Cas' eyes follow in his wake, both of them staring as Sam feels his skin prickle. Dean still has that fraternal smirk on his face, but Cas is watching him intently, mouth open and eyes wide, hungry.   Sam falters as he hooks a thumb into the waistband of his shorts. This must be how Dean feels at school, a million eager eyes on him as he weaves through a sea of eyelash-batting stares, all that attention washing over him. God, it's good, lights Sam up on the inside and makes him slow his hand, licking his lips and pulling the elastic down slowly. He lets his shorts puddle around his feet, kicking them aside and standing for a moment in just his briefs.   All eyes are on Sam for once, nearly naked and reaching down to cup his hand over his Y fly as he feels himself get hard, grinding his palm down and raking his eyes over Cas' smooth chest. It's Dean's habit but it feels good to put it on, testing and teasing and thinking that he could get used to this little drop of power on the tip of his tongue.   Shameless and susceptible as always, Dean's already got his hand on his dick, face slanted to the side a little impressed and a little appraising, master observing pupil. Cas is flushed, wavering steam and spotlights casting him into incandescent lust, damp curls matted to his forehead as he stares and chews his lips, wrecked and swollen before they even start on him and Sam feels like a fucking god. Those lips are gonna suck his dick.   It's not the wet-tipped thwap of Dean's thick cock but it's good enough for what he's got, pushing his underwear down and letting his dick spring free. Cas looks like his eyes are gonna bug out of his head as Sam bends down to slide his briefs down his legs, stepping out of them and grabbing his beer before he stands back up. Sam keeps his eyes on Cas as he steps into the water, so hot Sam can't help but let out a long “Ahhh” that just makes Cas crook his neck and squeeze his legs together, fidgeting and fussing as Sam's cock bobs underneath the bubbles. The jets that churn the water swirl Cas' shorts around, billowing gray over his pale thighs and obscuring whatever Cas is trying to clamp down on. Sam would bet his left nut that Cas has a hard-on.   When his feet reach the bottom Sam knocks back a sip of his beer. He doesn't particularly like beer, but Dean does and it makes his kisses sloppy and his hands always slide home quicker when he's breathing hot and hoppy against Sam's neck. Cas doesn't seem to like it much either, but he dutifully swills it down as Dean quirks an eyebrow and raises his bottle in a smirking toast. Sam turns to face him, drinking again just to show Dean that he can. Dean's lips are still smug and teasing, tracing around the rim of his beer but Sam can read his eyes, heavy-lidded and flitting over Sam's face, sloping over the bow-curve of his brother's mouth. He's got his arm sprawled out carelessly but the jut of his chin is beckoning, wanton. Needy.   Dean needs him and Cas wants him and Sam drinks it in, better than beer and the time Dean shotgunned a column of potsmoke into his mouth after the varsity game. He bounces up on his toes, weightless and warm and watched, floating over to Dean and settling down next to him. The cement of the seat feels pitted and scratchy against his bare ass but that's ok, he knows he won't be sitting for long, not with the palpable hunger in the air.   Dean's arm is cool when he lays it over Sam's shoulder, pulling him closer and running his hand into Sam's muggy hair. The easy catch and tug makes Sam shiver, turn his head up eagerly and whine when he feels the taunting drag of Dean's lips against his.   “Don't be a fucking tease, Sammy.” There's more pride in it than anything, half a chuckle and a rewarding slip of his tongue. He kisses open-mouthed and messy, lips wide and lazy with his eyes on Cas. Sam looks, too, catching sight of Cas with one hand in the water, still wearing those stupid shorts. Those need to go.   Sam shifts, floating with an anchoring hand on the rim of the tub to settle onto Dean's lap, facing Cas and spreading his legs. Dean's cock presses up against his back, slotting into the crack of his ass as Sam wriggles back and grabs Dean's hand. Cas' eyes trace along Sam's chest as he pulls Dean's hand down, cupping it over his hard-on and pressing it down. Dean huffs out an approving laugh into his hair, looking out over Sam's shoulder so they're both looking at Cas as Dean starts to move his hand. His thick fingers tug and pull on Sam's sac while the heel of his palm catches the head of Sam's dick and slides his foreskin up and down, pushing Sam back onto his own dick with every grinding push of his hand.   Where Sam would have bolted over and grabbed whatever he could get at it if he were the one watching, Cas just looks frozen in place, his nipples standing out pink and peaked on his slowly-heaving chest as he stares. Comfortable to look but still scared to touch, even if they all know he wants it. Politeness and permission aren't things that ever crop up with Dean, and Sam reminds himself that Cas needs subtlety, careful handling where Dean needs direct action.   “Come here, Cas, wanna show you something.” Sam smiles and slinks off Dean's lap, inching over until he's positioned where he wants to be. Cas takes a tentative step into the center of the pool, water rushing up to flush his chest a warmer pink as he slowly crosses the distance to Sam.   “You gotta take your shorts off for it.” Sam's hands itch against the concrete, holding himself back from pulling them off himself. But Cas looks pleased with the direction, smiling shyly and nodding, “OK.” Khaki floats to the top of the tub, forgotten as Cas stands there, holding his hand over his crotch until Dean chimes in.   “Aw, come on, Cas, we all got our dicks out, no fair.” Cas seems to relax under Dean's chiding attention, bringing his hands behind his back with some sort of new-found boldness.   “What do you want to show me?” Cas is hardly chatty, like anyone could get a fucking word in edgewise with Dean around, so Sam's never given much thought to Cas' voice. But fuck, it's sexy, deeper than it should be for his age, grit and gravel and gravitas that just makes Sam want to work him over until he's messy and panting and desperate.   Dean's turned towards them, eyes bright and bemused as he rolls his tongue over his lips, trapped between his teeth and this is working perfectly. Bolder at the poker-tell of Dean's face, Sam hops off the bench and goes to Cas, looking up and grabbing one of his hands to pull him over to where he'd been sitting.   The jets in the sides of the tub stream out steadily, churning up a bubbling wake that Sam drags Cas' hand into. “Ever sit on one of 'em?” Sam asks slowly, close enough to smell the icy blue of their communal shampoo in Cas' sweat- curled hair, loud enough that Dean hears him and groans out a low, deep- throated laugh.   “Sit on...?” Cas' eyebrows knit together, looking back and forth between both brothers like there's some joke he's not in on. Sam recognizes the worried rise of his shoulders, a move Cas pulled constantly when they were first thrown together. When Sam and Dean started tossing around inside jokes and inappropriate comments Cas would get tenser and tenser until he ran off like a shot, bustling into one of his hiding places and requiring days of gentle prodding to come back to the fold. He didn't do it much any more, but this is new for him, newer in a way it isn't for Sam. Cas can't ride roughshod over Dean's benevolent dictatorship the way Sam can, can't poke and prod and squirm and question until he gets his way. Cas needs to be led, and Sam learned from the best.   “Like this.” Sam keeps his grip around Cas' wrist, half to keep him from bolting and half to show Dean that he can. Balancing himself on the seat with his free hand braced between his legs, Sam tilts forward until the hot, hard stream of water pumping out of the jet tickles his nuts from behind and makes him gasp. Cas' mouth has settled back into a perfect O again, well-adjusted to the hot water by now but still unaccustomed to Sam writhing against the steady pressure licking against his nuts, his taint, his-   “Oh, fuck,” Sam groans, dropping Cas' wrist to steady himself as he feels the little jet-stream hit his hole, almost as good as Dean's thick, begged-for fingers as it laps against him. Sam knows this is a thing, that you can lick someone down there and if it feels half as good as he suspects when Dean does it Sam has found his new favorite hobby in life.   “Jesus, Sammy,” Dean glides next to him, eyes heavy and lips licked shiny-wet as he watches Sam ride the stream of water. Sam's hair is hanging over his eyes in a damp mess, sticking to his forehead as Dean grabs a wet hank and pulls his head back, not rough, just firm enough to makes Sam's mouth fall open. He can see himself in Dean's eyes, in Cas', how he must look, one of those words that runs thrilling-tingling wrong, want-it-bad through him. Slutty.   Just thinking it makes him moan and shudder, arching his back to get closer to the jet as Dean kisses his waiting mouth. His eyes fall closed as he rolls his tongue against Dean's in concert with the churning water, tickled at both ends and tasting Dean's beer and his breath and the chlorine tang of the pool. He doesn't need to see to know that it's not Dean's hand on his dick. The slender, more delicate fingers wrapping around his stiff cock are tentative and skillful where Dean's all grab and tug.     “Like that, Sammy?” Dean husks in his ear, looking at Cas and nodding a satisfied hum as Cas strokes him harder. “Fuck, look at you, trying to fuck the pool while Cas jerks your little dick off.” Sam bites his cheek and digs his fingers into the concrete, knowing he won't last much longer with Cas and Dean so hard and so close to him, hands and eyes all over him like they could eat him alive.   “He looks good, doesn't he, Cas?”   “Yes.” Cas' breath falters on it, caught in his throat as he flicks his wrist and twists over Sam's cockhead, and jesus fuck he's good at that, timing and technique and utter, perfect concentration as he pulls Sam right to the brink.   Dean sets his mouth to Sam's neck, kissing and nipping at that spot behind his ear that makes Sam's skin prickle gooseflesh against the hot water, shiver and nuzzle and pressure and tug until it's all one endless swipe, hot-wet push and pull and when Dean traces his finger around the liquid-lapped rim of Sam's asshole he doesn't stand a fucking chance.   Sam comes with a jerk of his hips and a sharp cry that Dean swallows up greedily, Sam's orgasm his to tear out for all that Cas still has his hand around Sam's twitching dick.   Sam floats bonelessly, glassy-eyed and shouldered over by his brother to lean back against the ledge of the tub. The air feels cool as he turns his face up, catching his breath and blinking himself steady until he hears Dean.   “Your turn, Cas.” Sam watches from the side of his eye as Cas takes his place in front of the jet, looking behind him like he's afraid it'll hurt. He lets out a startled, “Oh,” when he feels it, and another, longer and deeper sigh as he shifts his hips. “Ohhh.”   Dean slides off the seat and turns to press himself in between Cas' legs, reaching back to lay a hand on either side of his ass. Sam's head still feels heavy and muggy but he turns it to watch as Dean leans in to kiss Cas, licking along the seam of his lips before tonguing inside to the wet space that he'll share with Sam when he's ready.   Cas' spine arches in a graceful curve to disappear beneath the water, the outline of Dean's hands on his ass diffracted and out of proportion as he pulls Cas open. Sam's dick stirs back to life as Cas moans, canting his hips back into Dean's grip and kissing him eagerly.   Sam's extensive range of fantasies about sex, like actual sex-sex, generally featured Sam on the bottom, stretched and split open on Dean's thick, slick cock. Watching Cas writhe into every exposing lattice-pull of Dean's hands, bucking against the water pressure like it's not nearly enough, Sam thinks about all that tight heat pulling his dick inside, clenching around him and holding him tight while he blows his load, like it does for Dean. Cas is so fuckable like this, open and desperate and beautiful.   Cas hums when he kisses, soft hmmms that he sighs out in time with each pull of Dean's hands. He's mid-way through one of them when Dean pulls back, licking his lips and arching an eyebrow. “Feel good, Cas?”   “Yes,” Cas answers softly, eyes barely open as he watches Dean's mouth, pupils gleaming black in the pool light as he traces over the full curve of Dean's lips. He looks hypnotized, a swollen-lipped somnambulist ready to do Dean's bidding and Sam finds himself mimicking Cas' expression because he's not sure he's ever seen anyone look so absolutely lustful before. He's gorgeous, and if Sam didn't know Dean was setting Cas up for something (Dean never asks questions without knowing the answer) he'd crawl right between them and press his mouth to Cas' slack, wet lips.   “Want something more, don't you?” Dean's voice is low, thick as he asks a purely rhetorical question against Cas' trembling lips. Sam inches in closer, hop and float along the pebbled bench until he's right there, close enough to see Cas' eyes widen when he turns to look at Sam.   “I, um, it's, oh,” Cas protests feebly as Dean pulls him in, the hands on his ass pushing him forward until he's standing face to face with Dean, cocks lined up as Dean presses him close and kisses him deeply. Sam's eyes follow Dean's hands, one of them gripping Cas' ass until Sam can see the indents of his fingers, tan against Cas' pale skin. Dean's other hand slides up Cas' back, his fingernails dragging along the furrow of Cas' spine up-up-down, up-up-down until Sam is shivering just watching them. Cas must be a mess.   “S'ok, Cas,” Dean says, honey-sweet and soft. “Sammy wants to see.” Dean's fingers card through the damp mess of Cas' curls, tugging gently and making Cas arch his back like a cat. Dean's other hand disappears into the cleft of Cas' ass, doing something that makes Cas gasp and throw his head back.   Cas' eyes catch Sam's over the pale curve of his shoulder, all wide blue and fluttering eyelashes as Dean scratches and pulls at his hair. He does the same thing to Sam so he knows how Cas feels, shaky and struggling to form words because there is nothing more distracting than Dean's hands when he's feeling determined. Dean's mouth is tracing up the turned arch of Cas' throat, catching and sucking at each inch of exposed flesh, Cas letting out a throaty whine after each press of Dean's lips that makes Sam's dick throb.   He's hard, again, not that it ever takes long, and Sam can't help but press a hand to himself just to get something, some friction to ease the itch inside him as he watches Cas squirm and beg wordlessly for more. More, Sam needs more, too, just a touch, and his hands are out in front of him before he even knows it, anchoring his palm to Cas' back as he closes the few inches between them and presses a kiss to Cas' shoulder. He looks up through the stray bangs hanging in his face, nodding at Cas and brushing his lips against damp, gooseflesh skin.   “OK.” Cas says it softly, syllables lost in a huff of breath as Dean draws his hand back up, pressing it to Cas' side. He kisses Cas again, one last rake through his hair before he brings his other hand down to bracket the slim curve of Cas' waist.   Sam settles down onto the bench again, watching as Dean nuzzles Cas' head up, kissing a collar around his neck as he slowly turns Cas around. Cas keeps his eyes closed, head falling back to rest on Dean's shoulder as he pirouettes through the water and comes to face Sam. Dean's hands run possessively up the flushed plane of Cas' chest, but his eyes are all for Sam, smile crinkling the corners as he licks his lips and runs his tongue up the column of Cas' bared throat.   “He's pretty, isn't he, Sammy?” Sam can just see the flush spreading across Cas' face, his eyes slitting open to look down at Sam, plush lower lip worried between his teeth.   “Yeah,” Sam answers, wanting to agree because, fuck, yes, Cas is pretty, hair tousled and face flushed pink and lips just begging to be kissed, used, sucked raw and red and streaked white and shiny. But Sam knows this is dangerous territory, this business of prettiness, sometimes a compliment murmured against Sam's neck as Dean traces his thumb over the curve of Sam's pretty lips, other times a tease when Sam takes too long in the bathroom doing his pretty girl hair. Johnny McEnroe had a split lip to testify to how Dean reacted to being called a pretty-boy.   “He looks hot.” Sam settles on a clearer alternative, sitting up on his knees and shivering as the steam curls off his skin. His dick bobs just below the water, stiff and throbbing as he watches Dean slide his hand down Cas' stomach. Cas' cock is hard, flushed a deeper red than his pool-pinked skin. Sam can't see it, but he can imagine the generous drop of precome that must be coming out as Dean wraps a hand around it and squeezes up towards the head, matching it with a deft tug at Cas' nipple. It's a dirty trick and it's one of Dean's favorites.   “You wanna kiss him?” Another tug, squeeze, pull and Cas is groaning, mouth open like he couldn't remember to close it if his life depended on it. Sam inches forward, licking his lips and pushing his hair back from his face. Cas blinks his eyes at him once, twice, slitting them closed again as Dean slides his thumb over the head of Cas' dick.   Sam's arms rest over two sets of shoulders as he leans in, catching the jagged little breath Cas lets out while Dean works him over. Cas' lips always look chewed-over and scratchy but they're soft against Sam's tongue as he runs it over each one, teasing his way inside. Sam can feel Dean's breath hot against his ear, sighing out encouragement and pushing Cas closer.   Cas' teeth tickle against the tip of Sam's tongue, his own darting out tentatively to curl against Sam's. Cas starts to moan again, soft and thrumming into Sam's mouth. Sam knows it's weird to think that it's so cute, this little kitten-purr that Cas hums out while Sam kisses him, but it's sweet and adorable and so open, like he's lost in the moment and nothing else matters.   Dean had seen to it that Cas was taken care of once he'd accepted that they'd be sticking around for a while. School was never easy for Sam, but Cas had it a million times worse. Dean had solved that pretty quickly, singling out the worst of Cas' tormentors and blithely explaining to a group of doe-eyed girls that the only reason Tommy Phillips knew that Cas was gay was because Cas had been bored and let Tommy suck his dick. In hindsight, it was smarter than beating the guy up or denying the obvious fact of Cas' sexual orientation. But Sam hated rocking the boat, and he'd made a half-hearted attempt to chew Dean out for it before Dean had given him a withering glare in the school parking lot.   “He's ours now. We have to take care of him.” That had been that.   Sam starts, pleasantly surprised as he feels Cas' hand against the small of his back. He pulls Sam closer until Cas is pressed in between them, Dean's hand on his dick rapping back against Sam's own hard-on. Sam slides his hand down, palming against wet skin until he lays his hand over Dean's. Cas is theirs and they always take care of their own, one of the first lessons Sam had ever learned from his big brother.   “Cas is pretty all over.” Dean says it molasses-slow and deliberate, eyes glinting as Sam pulls off Cas' mouth and looks at him.   “Oh, yeah?” Sam means to put a lot more swagger in it, but it's more shaky than seductive, dizzy with thoughts of every pink and pretty part that Sam wants to see.   “Mmm-hmm.” Dean nods and smiles, his hand still jacking Cas' dick as he nips at his ear, eyes on Sam. “He's got a nice cock, doesn't he?” Dean gives him three more quick strokes before releasing him, arching an eyebrow as Sam stares down between them and nods his agreement. Cas' cock isn't quite as long as Dean's, but it might be thicker, he's not quite sure, and Sam feels his fingers curl against the rim of the hot tub as he thinks about wrapping his hand around it, stretching his mouth over it and making Cas really purr for him.   “He's got a pretty little asshole, too.” Cas whimpers at that, no other word for it, and Sam realizes that he's lost track of one of Dean's hands. Sam feels his heart skip-thump in his chest, pretty little asshole, fucking christ, hearing Dean say it sounds so bad and wrong and sexy, like Dean just raked his nails over all the secret, dirty things that Sam thinks about. Sam's cock jerks as he bites his lip, reaching out impulsively to cup Cas' face in his hand.   “I want to see.” Sam's own voice comes out awfully close to a whimper, closer to begging than anything else. Sam's trembling all over as he kisses Cas again, sloppy and hard as he digs his hands into Dean's shoulders, pulling them both closer until Cas has to reach a hand out to steady himself against the ledge. Cas buries his face in Sam's neck, black tangles of hair brushing against Sam's cheek as he leans over to kiss the smug look off Dean's face. No one's really in control any more, not when they're all pressed together in a wet pile, everyone hard and hot and buoyed by the sheer weight of each other's bodies and the bubbling water.   They half-fall, half-float onto the seat of the tub, Dean urging Cas up onto his knees until he's bent over the ledge of the pool, his ass up above the water and his legs spread wide. Sam drifts to one side to make room for Dean until they're each straddling a leg.   It is pretty. Sam feels frozen, throbbing so hard he can't move as he watches Dean palm Cas' ass apart with a confident familiarity that bypasses any trace of jealousy in Sam and dives headlong into desperate, aching need. Cas' hole is small, furrowed skin folding in tightly as Dean traces over it lazily. His balls hang down, heavy and larger than Sam remembers, dipping into the water. Sam rakes his eyes over the straight seam running up the middle, sparse hairs curling damp around it where it disappears into the furl of pink muscle. Each breath out of his mouth feels shaky, straining with the effort of holding back the million different things the sight of Cas like this makes him want to do.   “Told you.” Dean smirks at him over the taut line of Cas' shoulder blades, bone winging out under skin as their step-brother ducks his head and arches his back. Sam bites his lip to quell the trembling and nods, following the plush curve of Dean's lips as he kisses right along the jut of Cas' shoulder.   “Get me that bottle, Sammy.” It takes Sam's limbs a few seconds to respond, sluggish and stuck, but he manages to float over to the hand-rail and grab the slim tube Dean had left there. Sam only has hazy ideas about what it's for, but he's always been quick on the uptake and he hands it back to Dean shaking with anticipation.   “See, you can't just stick it in there.” Dean flicks the top open and regards Sam, settling into his teacher-mode. Dean always liked showing him new things, and he looks like he's relishing every second of this little demonstration.   “Remember what I told you about fucking a girl, right?” Dean taps his finger against Cas' ass like he's waiting for an answer.   Sam's smirk isn't as sexy as Dean's but it does the trick. “Lick it before you kick it.” Sam over-annunciates every consonant, because sometimes Dean says things that sound fucking retarded.   Even Cas has to laugh, turning to look at Sam over his shoulder and snorting against his arm. It feels good to see Cas so relaxed, and Sam settles in closer to Cas as Dean shoots his best “you little shit” face at Sam.   “Well,” Dean sighs like the world's most put-upon sexpert, “it's the same thing.” He drizzles a thin stream of shiny liquid over his index and middle fingers, setting the bottle down and smearing the clear stuff down to his knuckles. Dean wiggles his eyebrows and his shiny fingers at the same time. “You have to get it wet first.”   Sam had figured as much, but his eyes still go wide as he watches Dean slide two fingers right inside, twisting his wrist and rocking his hand until Cas throws his head back and moans. Sam doesn't want to look away from the sight of Dean's fingers disappearing into Cas but he can't help himself, he has to see Cas' face.   It's not like Sam doesn't know anything about butt-sex. He'd been watching porn with Dean for years, and his big brother was a fan of anything with “gang” and “bang” in the title. But they never showed this kind of stuff, fingers slowly pressing inside, hands stroking up along ribs as hushed little noises get whispered. Sam was used to seeing something tan and blonde sit down on a dick with a fake smile plastered on her face, lips pouted and frosted blindingly pink.   Cas couldn't look more real. He doesn't even look hot, not in any sense Sam is used to. He looks wild, hair sticking out in eight million different directions, his eyes half-shut and his mouth slack and wet. The noises he's making don't even sound human, chest-deep moans and grunts that make Sam's hair stand on end. He doesn't even realize that he's rubbing his dick against Cas' leg until Dean reaches down to tug on it, more to get Sam's attention than get him off.   “Wanna help me, Sammy?” Dean looks at him through his eyelashes, shoulder rolling as he keeps fingering Cas. Sam blinks and opens his mouth to say something, finding it easier just to nod and move behind Cas.   Dean's fingers move in and out of Cas' hole faster than Sam has ever tried on himself, certainly faster than Dean's ever done it to him. Cas lets out dirty- wet noises with each sink of Dean's fingers, coming back to meet them hard enough to make his balls slap against the water. Sam feels a small surge of jealousy that Dean's never done it like this with him, but it quickly dissipates as Dean grabs his hand and drizzles the slick stuff onto Sam's first three fingers. He'll get Dean to do this to him soon enough, and right now the thought of touching Cas like that is enough to make Sam's dick twitch against the hot water whirling past him.   “He can take more.” Dean says it low and dirty, the kind of dirty that sounds like Dean's highest praise and always makes Sam warm up on the inside. It seems to have the same effect on Cas, his legs spreading a little wider as he wordlessly groans something agreeable.   Dean slows his pace and buries his fingers to the second knuckle, curling them and pulling down until Sam can see a glint of pink. “Spread the lube on your fingers, all over,” Dean orders. Sam brings his other hand out of the water to spread the sticky shit, the lube, down his fingers just like Dean had. It feels cold against the night air but it quickly warms up in Sam's hand.   Tentatively, Sam reaches his hand out, the pad of his index finger brushing in between Dean's knuckles as he slowly, slowly presses it inside Cas. He keeps expecting to feel some resistance, for Cas to tell him to stop or Dean to tell him he's doing it wrong, but his finger just glides inside like Cas had been waiting for it all along.   Cas is warm inside, which Sam knows both from basic biology and his own limited experience, but it's just different when it's someone else's body. Cas feels like he's burning up, hot and wet, fuck, so wet and slippery that Sam's drawing his finger back out and sinking it in before he realizes that he's groaning just like Cas.   Dean murmurs out an encouraging noise and slides his own fingers back just to sink them in again, pulling down once more and jutting his chin at Sam. “Just like that, Sammy, good.” Sam bites his lip, dick throbbing at Dean's approval and the tight, wet heat of Cas around his finger. “Now give him more,” Dean breathes against his ear, pulling his fingers out and floating over to sit next to Cas.   Cas whimpers and bucks his hips back, and Sam grabs onto Cas' waist with his free hand because it just seems like the right thing to do, to steady them both before he takes a deep breath and dares to add his middle finger. The way Cas sighs and squirms back as he sinks them both in is delicious, and Dean's chuckle is warm and muted through a sloppy kiss against Cas' mouth.   Sam fucks his hand in faster and faster, goaded on by Dean's “C'mon Sammy, that's right,” and Cas' guttural groans, the arch of his stepbrother's back giving him enough confidence to find his voice and a third finger.   “That feel good, Cas?” Sam tightens his grip on Cas' waist, lean muscle stretched taut under his hand. “You like that?” A third finger slips in easily, back and forth until Sam folds his pinky under and sneaks it past home, marveling at the way Cas tightens against it just to let him in and growl out a long stream of meaningless bullshit against Dean's chest.   Dean sits up on his knees, looking over Cas' back to watch Sam's fingers pump into Cas' stretched hole, the look on his face anything but smug for once. “Jesus fuck, Sammy...” Dean scrubs a hand over his face like he needs to clear his eyes, looking down again before he reaches down to wrap a firm hand around the base of his dick.   Sam keeps fucking Cas with his hand, desperately wishing he could put a hand on his own dick but not wanting to relinquish his contact with Cas. Dean's eyes are wide, his lips set in a perfect red O as he watches. He shakes his head and looks back and forth between Sam and Cas, licking his lips before leaning down to brush his mouth against Cas' ear.   “I want to watch Sammy fuck you, Cas. You want that?” Dean slides his eyes over to Sam, not bothering to ask him as well because the look on Sam's face is probably visible from space. Sam's pretty sure Cas' handjob is the only reason he doesn't blow his load just hearing Dean say it, digging his hand into Cas' side just to keep himself from keeling over.   “Christ, yes, just fucking do it,” Cas almost snarls over his shoulder, his eyes narrowed down to blue-black slits and his teeth bared. Dean licks a stripe up the side of his neck before pushing off the ledge of the tub and coming to stand next to Sam.   “Get up behind him,” Dean urges, nodding with satisfaction as Sam perches on his knees in between Cas' legs on the seat. The air feels cold against his skin, tender and starting to wrinkle from the hot water. Dean's hand wrapping around his dick is warm and wet in contrast, slicking him up and grasping firmly to line the head of his cock up with Cas' hole.   “Just push it in slow,” Dean whispers against his ear, pulling his hand back and skidding his palm up Cas' side. “Watch out, Cas. This might tickle a little.” Sam can't even be bothered to snark back at Dean's dick jokes, not now, not when he can feel the clenching pull of Cas' ass ghosting over the head of his dick, precome leaking out to add to the slick mess as it sinks in that he's going to fuck his stepbrother. This is a million times better than the blowjob he was hoping for.   It had taken Sam a while to talk Dean into sucking his dick, but once he had it was easy to get Dean to do it. The first time, he'd never imagined something could feel so fucking good on his dick, tight and hot and sloppy-wet and a thousand times better than any spit-in-the-palm handjob. As Sam pushes the head of his dick through that tight ring of slick muscle, his legs start to shake and he looks over at Dean with eyes like saucers. No blowjob in the universe could have prepared him for this.   Sam had measured his dick once, stroking himself until he was bursting hard before lining his cock up with a purloined ruler, sick of Dean's “cute little prick you got there, Sammy,” comments. Right now Sam can feel the wet push of all five and a half inches as he slowly sinks into Cas, and this is just fucking insane, that anything can feel like this, like every nerve in his body packed up and moved to his dick and they're all getting squeezed into this hot, tight, impossibly small space and jesus fucking christ how the fuck does Dean fit in here? Just thinking about Dean's cock, shiny and thick and so fucking big splitting Cas open like this makes Sam whimper and dig his hand into Cas' side as he brings his hips flush with the smooth curve of Cas' ass.   “Good boy, Sammy.” Dean molds himself to Sam's back, his nose pressing in between Sam's shoulder blades. “Fuck, baby.” Dean kisses him, running a hand down his side and sliding it over to cup Sam's ass. “You like that, Sammy? Feels good, huh?” Sam tries to moan out a yes, still too shaky and desperately afraid that he's gonna blow his load too soon. Dean just mumbles, “Yeah, thought so,” against his back, trailing his finger in between Sam's ass cheeks and circling his thumb around Sam's hole.   Sam's hips jerk forward at the touch, making Cas arch his head and look back at Sam, lips swollen red and parted open as he groans out, “Do it, Sam.”   Sam snaps his hips again, letting out his own groan as he feels tight pressure slip-slide over his dick, Dean's thumb still pressing against him, almost slipping inside every time Sam draws back. Cas huffs and rocks himself back into every thrust, and Sam feels his nuts draw up just thinking that Cas likes this, that he's doing good and this won't be the last time, which is good because Sam can't last much longer, not when he feels the brush of Dean's mouth against his skin.   “That's it, Sammy,” Dean mumbles as he sucks a wet bruise on Sam's shoulder. “Fuck him open for me, c'mon.” Fuck, fuck, Dean and his fucking mouth. Sam tries to slow down, hold himself back so he doesn't bust a nut in two seconds but Cas just pushes back on him harder, making their bodies slam together with a wet sound that Sam wants to listen to for the rest of his life.   “I'm, oh fuck, fuck I'm gonna, gon-” Sam breaks off with a strangled cry as Dean pushes his thumb inside, flooding Sam with more sensation than he can handle, his head falling back to knock against Dean's as he thrusts his hips forward and comes. “Yeah, Sammy, come on, get him all wet for me, jesus christ, so fucking hot, I can fucking feel it,” Dean grits out against Sam's back as he pushes his thumb in deeper. Sam feels like he could vibrate out of his skin, hips stuttering and stomach clenching as he jizzes like it's shooting out of his eyeballs.   Dean's hands are firm on his waist as he pulls Sam back, settling him on the bench and climbing up to take his place behind Cas. Sam sits up so he can spread his arms across the rim of the tub. He smiles as Cas lays his head on his chest, kissing at his neck softly before looking back at Dean.   Dean's dick bobs up from the water flushed and hard, deep red and dripping wet, beading up a fresh drop of precome to match the water trickling down the thick shaft of it. Dean reaches out for the bottle of lube and squirts a thick stream of it onto his dick, biting his lip and spreading it around.   “Holy fuck, Sammy,” Dean whispers under his breath, a hand on either side of Cas' ass spreading him open. “It's fucking leaking, jesus.” He sinks two fingers into Cas easily, hole come-slick and open, Cas hissing against Sam's neck as Dean curls his fingers and pulls them out. They're crooked at an angle as he brings them up slowly, shiny-wet and dripping with as much of Sam's spunk as he can hold. He parts them in front of his mouth, letting the wavering light catch on the strings spiderwebbed between his fingers.   Dean's eyes are heavy and dark as he grips his cock and presses the wet head into Cas' hole. Sam can just see over the curve of Cas' ass, enough to make his breath catch as he watches Dean sink in slowly, sucking two come-wet fingers into his mouth at the same time. Sam feels it again, that hot flush under his skin as he watches Dean rock his hips forward, face dark with lust and all trace of arrogance gone as he swirls his tongue around his fingers. Sam's chest is tight, unfamiliar pride straining against his ribs with the thought that he did this. Dean and Cas are fucking now but Sam's inside them both.   Dean's rougher than Sam was but slower than he expected, sinking in and out and circling his hips as Cas moans against Sam's shoulder, mouth working like he's trying to say long-forgotten words. He grunts as Dean hitches a leg up and speeds up, Dean smiling as Cas grips his hands tightly against the concrete and keeps warbling out those dirty sounds that rise in pitch with every smack of their bodies together.   “He's gonna come, Sammy, come while I fuck him.” Dean's voice is ragged, breath shaky and thick as he rolls his stomach and works Cas faster and faster. “That's how he likes it best, isn't it Cas? Don't even need a hand on your dick, just need my cock up inside you.”   Sam can't even process what half that means, not when all he can hear is the wet thwap of Dean pumping into Cas fast and steady, Cas moaning against his neck and writhing back for it like something feral. The shy kid Sam plays video games with is long gone, hand digging into Sam's arm as he throws his head back, teeth clenched together and eyes squeezed shut as he keens out a strangled noise like he's-   “Oh fuck, Cas, fucking god, feel it, fuck,” Dean growls, eyes rolled back in his head as he snaps his hips and bites his knuckle in between his teeth. Sam looks down just in time to see the last spurt of jizz arcing out of Cas' dick, twitching and pulsing into the empty air. Jesus fuck, he'd thought Dean was just talking shit, how was that even possible?   Dean groans and grits his teeth, relentless pace skidding into jagged snaps of his hips as the muscles on his neck cord out and strain against his skin. Beads of sweat trickle down his forehead to mix with the dewy residue of steam and water. His eyes are wide now, focused on nothing but aimed at Sam as his mouth falls open. Sam can see it in Dean's eyes, the coiling spring of pressure mounting in the pit of Dean's stomach, spreading over Dean until he stops abruptly and buries himself in Cas, pulling him back tight and filling him up. Sam's seen this face a million times, nose-to-nose as Dean huffed and puffed his way closer, but never like this, detached enough that he can watch every nanosecond of joy wash over Dean's face and light him up. He'll never say it to his face, but Sam knows that he's never seen Dean look so beautiful before.   Dean heaves for breath and holds Cas back as he looks at Sam, muscles on his stomach dancing as he jerks out the last few spurts of his orgasm. Sam's mouth waters with the disgusting-hot thought that Dean's come is mixing with his, filling Cas up with both of them until he needs to see. Dean grunts with surprise as Sam gets up on his knees next to Cas, reaching a hand down in between to run his finger around the tight juncture of their bodies.   “Look,” Dean sighs, slowly drawing his dick out until the crown slips free. “So fucking hot.” A steady stream of white runs out after it, creamy wet and more obscene than anything Sam has ever imagined. He slips a finger in, earning a deep groan from both his brothers as he draws it back and sucks it into his mouth. It's strange, the familiar taste of Dean and the fainter trace of his own spunk tainted with the petrochemical tang of the lube and a deeper, murkier taste that Sam recognizes with a thrilling twist of his gut as Cas.   Sam groans as Cas twists around and sits back on the seat, rubbing at his knees and staring at Sam with wide eyes. Sam pulls his finger out of his mouth with a wet pop, turning to Cas and smiling breathlessly at him before leaning down to lick into his mouth, share it because anything of theirs belongs to Cas, too, and Sam doesn't have the words for how he feels right now, he just needs them both.   Dean smirks down at them, asinine grin back on his face but underneath it's loving, proud, and Sam moves before he even thinks about it. He just has to know.   Dean's face is placid, waiting for Sam to come kiss him, but he quickly drops his jaw in surprise as Sam turns around and goes right past his face, sinking down to his hands and knees and sucking Dean's soft, wet dick into his mouth.   “Holy shit.” Cas' voice is hoarse and scratchy even for him, and Sam's spine tingles with the thrill of doing something that he knows must be wrong. It's sticky and salty and Sam can practically feel Dean staring, and he can definitely hear him gasping as Sam flattens his tongue and slurps the last clinging rope of spunk off the underside of Dean's cock.   Sam's chest heaves as he sits back against the rim of the tub. He can feel a shiny stripe of something on his cheek cooling against the night air, and he almost goes to wipe it off before deciding to leave it. He likes it, likes how Dean and Cas just stare at him and blink their eyes like they don't know what he's going to do next.   Cas breaks off first, sighing and pushing off to dip himself in the water. He stands up and shakes his head, sending a spray of water flying in every direction. Sam laughs as one lands right in Dean's eye.   “Ugh, dick.” Dean wipes his eyes and makes a face at Cas before he sits next to Sam, pulling him into his side and scratching his fingers through Sam's hair.   “That was nice.” Cas nods his head, seemingly satisfied that he's said enough. “I'm famished. Should we order some Chinese food?”   “Yeah, Cas, that'd be great. Can you take care of it?” Dean leans his head on Sam's, looking at Cas sideways and smiling. “'Preciate it.”   Cas smiles and looks back and forth between them, tilting his head. “Of course.” He fishes his trunks out of the water, wringing them out as he starts up the hot tub stairs. Sam half-expects him to put them back on. Cas is weird enough to manage modesty after getting fucked twice in a row. But to Sam's surprise, and a certain pride that their good influence is rubbing off on him, Cas tosses them over a chair to dry. He still grabs a towel before he heads into the house, wrapping it around his waist and padding back across the patio.   Dean watches him leave before pulling Sam onto his lap. Dean sinks lower into the water so Sam can face him, straddling his hips and resting their foreheads together.   “Jesus, Sammy.” Dean runs his thumb over the shiny trail dried to Sam's cheek, a smile quirking up the corners of his mouth. “You good?”   Sam rolls his eyes and sighs. “Ye-aaah.” Sometimes Dean asks the stupidest questions.   Dean laughs and tugs on the lock of hair hanging in Sam's face. “Bitch.”   “Jerk.”   Dean kisses him suddenly, his hand hot against the back of Sam's neck. Sam can feel him smiling.   “Well good, because I, uh...” Dean blows a breath out through his lips, tickling against Sam's nose. “I really wanna do that again.”   Sam knows an opportunity when he sees one. He pouts his lips, just a little, and runs his fingernails up through the soft spikes of hair at the nape of Dean's neck. “I wanna do it again, too, but I just...” Sam trails off and bites his lip, looking down into the water.   “What, Sammy?” For all that Dean acts like a total fuckface most of the time, he's a complete girl when it comes to the puppy eyes.   “I want you to do me next time.” Sam bats his eyelashes, keeping his eyes trained on the water and ducking his head. He gives Dean another scritch and sighs. “Unless you don't want to. I mean, I guess I understand if...” Sam takes a deep breath and looks up at Dean from under his bangs, hoping he's not laying it on too thick. “If you like Cas better than me.”   “Sammy, no!” Dean pulls him in with a bear grip and buries his face in Sam's hair, shaking his head. “Never, Sam. Never. I care about Cas, yeah, but it's different. He's older, I mean, fuck, Sammy, you're only tw-”   “So?” Sam always tries to nip that shit in the bud. “What does that matter? I'm not stupid, Dean, I know what it means. And I won't tell anyone. Besides,” Sam sighs, kissing the flustered look off Dean's face. “I really, really want it.”   Dean's eyebrows draw together, eyes closed as he takes a deep breath. “Sammy-”   “Look, I don't mean, like, right now.” Sam knows that sometimes, it's better to play a long game with Dean and quit while he's ahead. “Just, you know, soon, ok?”   Dean relaxes under him, rubbing his hand over Sam's back and arching an eyebrow. “Yeah, soon enough, alright?” Dean narrows his eyes. “First you gotta get used to it, like practice. Cas has some stuff, maybe we can show you tomorrow, OK?”   Sam tries to keep his eyes from going wide as he pictures Cas' “stuff,” images of bright plastic things he's caught sight of in porn flashing through his mind. “Yeah, that'd be cool.”   “Now I don't know about you, but I am fucking starving.” Dean rolls his neck and gives Sam a peck on the lips. Sam slides off his lap and floats over to the stairs, shivering as he steps out onto the flagstones. Dean's close behind him, dripping wet and stark naked, not even bothering to grab a towel as he saunters towards the house.   “Who was General Tso, anyway? You always know nerdy shit like that.” Dean looks back as Sam wraps a towel around his chest. He smiles and rolls his eyes, picking up his pace. “Better hurry up, Shrimptoast, or Cas and I are gonna eat all the egg rolls.” Dean jogs off into the house, leaving Sam behind to listen to him laugh and watch him go inside. He smiles and takes a second to congratulate himself. Dean's not thinking about Dad any more. He's happy and just thinking about the three of them, and that's just the way Sam wants it.   Sam takes a deep breath and draws his towel a little tighter, savoring the thought that soon he'll be the one getting fucked in the hot tub. He's planted the seed, and it's only a matter of time before Dean caves. And Sam's pretty sure he's got an ally in Cas, which can only make it easier.   Sam tucks his towel in and heads back to the house, wondering just what kind of stuff Cas has hiding in his bedroom.             Please drop_by_the_archive_and_comment to let the author know if you enjoyed their work!