Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/585546.
  Rating:
      Explicit
  Archive Warning:
      Underage
  Category:
      M/M, Multi
  Fandom:
      Supernatural
  Relationship:
      Castiel/Dean_Winchester, Dean_Winchester/Sam_Winchester, Castiel/Dean
      Winchester/Sam_Winchester
  Character:
      John_Winchester, Original_Female_Character
  Additional Tags:
      Underage_Character, Comeplay, Blow_Jobs, Hand_Jobs, Snowballing, Underage
      Sex, Barebacking, Frottage, Threesome_-_M/M/M, Voyeurism, Angst,
      Homophobia, Community:_homebrewbingo, Step-siblings, Sibling_Incest,
      Weecest, weecestiel
  Series:
      Part 2 of Stepbrothers
  Stats:
      Published: 2012-12-07 Words: 4167
****** Four Days Later ******
by saltandbyrne
Summary
     Cas had watched them more times than Sam or Dean would ever know,
     soft-footed and desperate for more than the swollen-mouthed seconds
     Dean threw at him. But he'd never watched like this, with Sam pulled
     onto Dean's lap, eyes slitted shut as Dean pawed at his flat chest
     and sucked on his neck.
     (Sam is 12, Cas and Dean are 16. Brief mentions of kissing and
     frottage when Sam is ~10)
Notes
     This is all snappapple's fault.
 John's been gone for four days when Dean does it.
 
Something has felt different for the past few days, setting the cat-hairs on
Cas' neck bristling and curious. It's nothing explicit, nothing as
straightforward as Dean's usual gruff notice that they were gonna smoke pot
tonight, or that Cas had better take a really good shower. It's not really Dean
at all. It's Sam.
 
Little looks and sidelong glances, stolen from behind Dean's ever-present warm
bulk between them. They'd been grabbier than usual, tense from the looming
school year and the vast emptiness of the house that Dean kept frigidly cold
with a surreptitiously dialed-down thermostat. Dean joked that he liked how it
made Cas' nipples stand up, how the goosebumps on his pale skin made him look
like a little chicken cutlet. Dean's endearments were strange sometimes.
 
Cas has his own suspicions about Dean's insistence on “60 degrees and fuck the
trees.” Sam doesn't seem to notice that he curls into Dean's side the second
his brother appears next to him, gaze on the TV unbroken as he shrugs his bony
shoulder into the musky warmth of Dean's armpit. Cas notices, though, just like
he notices everything about his favorite case-study: The Winchesters.
 
There's something to this, the cold air and the recalcitrant refusal to play
outside in the summer sun like they were supposed to. This house and everything
in it belonged to Cas' mother, but there was no question that it was Dean's
habitat. Rather than ask for the affection Cas knows Dean craves like sunshine,
he just cranks down the temperature until both his brothers crave his touch
against the cool brush of their home.
 
Dean is masterful in his way, adaptive and plastic in a sense that someone who
knew less about evolution than Cas does would call predatory. But Dean is a
survivor, and he won't fight for anything he needs when he can just let it come
to him. The fact that he's completely unaware that he does this only makes Cas
crave his companionship more, fascination and admiration and attraction all
wound up inside him until he loses his breath just thinking about Dean.
 
Cas had known he was gay as long as he'd known about sex. There was never a
mommy in his imaginary family units of recycled wood and ethically-sourced
cotton. His mother had seemed thrilled, a new addition to one of the many ways
Cas was exceptional and different. Nevermind that he barely spoke to other
children, that sometimes his head hurt so much from thinking that he had to sit
in the dark until it went away. Just another sign of latent genius, another
specialist called in for interviews and boring tests with people's faces on
soft felt squares.
 
Sam was quiet in the same way, especially during those first few weeks. They'd
all been thrown together and left to fend for themselves, all their parents'
talk of eloping and whirlwinds totally meaningless as they'd navigated this new
hierarchy. Like there'd ever been a question that this family was Dean's.
 
“Cas, get Sammy a coke.” Cas' eyes focus back onto his book, thrown aside to
stand up and pad off to grab a soda from the massive stainless steel fridge.
Cas can remember when it was filled with quinoa salad and kale and organic
fruit snacks, but now it's coke and pizza on a good day, half a six-pack and
some old ice on a bad one.
 
“Get one for yourself, too,” Dean yells, so Cas reaches in for another.
 
Cas is familiar with bullying. He's small, and he's queer in every sense of the
word. Even the progressive private schools his mother had painstakingly
selected for him had other children in them, and most children are vicious,
cruel little gang members. Cas knows what it's like to be bossed around.
 
This familiarity with small-scale abuse made it easier to recognize that Dean
was something different. Cas may in fact be one month older than Dean, but when
the Winchesters had arrived, Dean had taken one look at him and started
treating him exactly how he treated Sam. Cas had dealt with his mother's book
tours and cocktail parties by hiding in the closet and alphabetizing dinosaur
species. Dean had apparently taken his own absentee parent issues in stride and
declared himself the paterfamilias, issuing orders and organizing their days
with a constant, vigilant attention that made Cas hurt for him sometimes. He
knew that Dean had to keep moving to fill up the empty spaces they all shared.
 
There's another look when he hands Sam the soda, something Cas can't quite put
his finger on. There are so many unspoken things between them, secrets and
half-secrets and truths that were best kept quiet, as far as he could tell. It
could still be difficult for him, navigating this mine-field of propriety,
toeing softly for the line in the sand where he belonged between them.
 
Sam and Cas had secrets of their own, things they'd seen that Dean didn't know
about. Cas knew that these were things he should never bring up, so he kept
them inside and saved them to call back when he needed something nice to think
about, something that was warm and so strangely simple for something Cas knew
should be abhorrent.
 
The dark had always been Cas' friend, everything muted and easier to manage
that way. “Hyper-acute eyesight, he's just such an exceptional boy.” Cas thinks
that other people just don't try hard enough to see in the dark.
 
The first time he'd seen them, two years ago now, Cas had been softly shuffling
by his mother's bedroom. He was fascinated by the sounds John Winchester could
elicit from his mother, the ragged groans and muffled sobs that drifted out of
their bedroom for those few golden weeks when he had a new father. This was
what sex sounded like. Cas knew that this was inappropriate, which merely meant
that he couldn't get caught. Stealth came naturally to him, learnt from a short
lifetime of evading unwanted attention and the endless tests and questions and
photographs his supposed genius had earned him.
 
He'd listened until John was softly snoring, the low rumble something new and
pleasant to Cas' ears. He knew that would be all for the night, so he'd turned
back to his room before a new sound caught his attention.
 
It was barely audible, quick and soft and wet like someone taking a bite from a
ripe peach. This was Dean's room, filled with movies and magazines and that
ripe, hot scent of his that had already started to haunt Cas. The door was ajar
the barest inch, just enough to beckon to Cas and his desperate need to see, to
know, to make sense of all these fierce new things swirling around inside him.
 
Dean's back was bare, the white expanse of it moving in a steady rhythm as a
pair of skinny arms wrapped around his neck. Even Cas couldn't see them in the
darkness, but he knew that Dean had freckles across the sun-kissed tips of his
shoulders. He'd seen them by the pool a few days earlier, and he felt each one
calling out to him like a homing beacon for his mouth.
 
It had dawned on Cas with an aching sort of clarity: This is kissing. Sam and
Dean were kissing, and all those delicious noises that pulled Cas in and curled
around his spine like a warm kitten were from their mouths.
 
The gasp Sam had made hit Cas right in the groin, and he'd almost doubled over
as he felt himself getting hard when Sam's bright little eyes fell on his face.
“Oh god, oh god,” Sam's mouth had gaped like a fish out of water, his head
snapping back and his body going taut. The rhythm of Dean's hand ceased and Cas
clapped a hand over his mouth as he took in what had just happened.
 
Sam had looked back in time to see Cas shaking his head, I won't tell, Sam,
hopefully evident in the set of his head and finger pressed over his lips. The
last thing Cas had heard as he'd silently retreated to the hall was the low
rumble of Dean's voice, “Good boy, Sammy.”
 
Cas was ruined from that night forth.
 
He'd known all about sex for a long time, had studied it with the same
intensity he gave to everything else that caught his interest. It was still
strange to him, how the other kids had known what he was before he did,
sniffing out all the right slurs to hurl at him, more painful for their ring of
truth. Many hours online had confirmed that, yes, Cas was totally fucking gay.
 
Dean hadn't seemed that way to him, but as Cas vividly imagined what Dean's
sure, able hands had been doing to Sam's little body, he wondered if Dean was
something else entirely, something touch-driven and insatiable and far beyond
the confines of orientation.
 
And Sam … Cas had tried to seek out the sense of injustice that should have
filled him. Sam was a child, for all his world-weary sighs and knowing hazel
eyes. But it wasn't just Sam, it was Sam and Dean, the two of them as
inextricably linked as two sides of a coin. As Cas had fisted his cock in the
shower, replaying that soft, wet sound over and over again, trying to fill in
the blank spots that the darkness had covered, all he could think was this is
what love looks like.
 
The bottle hisses out carbonation as Sam twists it open, blushing slightly and
mumbling out a “Thanks, Cas.” Cas is already half-way back to the other couch
when he hears another sound, soft and wet and achingly familiar by now. He
stops in his tracks and dares a look out of the corner of his eye.
 
This is some kind of test, surely. The one and only time Cas had brought up
what Sam and Dean did together, Dean had just glowered at him like he was going
to hit Cas, or worse, shut his door and never let him back in. “What about it?”
Cas had managed a weak “Nothing,” and dropped it, content to open his arms and
legs to Dean when he came in late at night, covered in the puppy-sleep scent of
Sam and a frustration that made him rougher and more reckless than Cas imagined
he was with his brother.
 
Cas had watched them more times than Sam or Dean would ever know, soft-footed
and desperate for more than the swollen-mouthed seconds Dean threw at him. But
he'd never watched like this, with Sam pulled onto Dean's lap, eyes slitted
shut as Dean pawed at his flat chest and sucked on his neck. Cas feels his dick
twitch just thinking about Dean's mouth there, slowly sinking back onto his
seat for want of any other direction.
 
He can hear himself swallow, clicking and stuck in his throat as he tries to
breathe normally. Normal means strange things to Cas, he knows there's nothing
normal about fucking your step-brother after he sneaks back into his own room
covered in his little brother's spunk and baby-sweat, but there were rules
about these things, there were things he wasn't supposed to do or talk about
and Dean's blowing them all to shit as he slides his hand into Sam's
sweatpants, green eyes lust-bright and wicked as he keeps his gaze on Cas.
 
It had been Cas who'd started it with Dean, screwing his courage to the
sticking point and marching into Dean's room. He hadn't even opened his eyes,
just pressed Dean back onto his bed and kissed him, open-mouthed and desperate
for it. He'd flinched and waited, because this had only ever ended one way,
with a hook to the jaw and a “fucking fag,” but sometimes they kept kissing him
afterwards so he knew it was worth the risk.
 
Dean hadn't done any of those things. When Cas had finally opened his eyes,
Dean was just smirking at him, tilting his head in a parody of Cas' own nervous
gesture and nodding with amusement. “Huh.” That night had been the first time
he'd ever felt someone else's hand on his dick, and he was fucking sold on it.
 
Dean's hand looks huge under Sam's sweatpants, moving up and down slowly as Sam
lets out soft hngh noises and bites his lip. Dean's eyes are still on Cas as he
slides his free hand under Sam's shirt, eliciting a deep groan that Cas
recognizes. Dean does the same thing to his nipples all the time and it makes
Cas feel fucking crazy.
 
He's still got the other bottle of coke clasped between his hands, condensation
sweating cold onto his fingers. Cas squeezes it tightly, holding onto the cold
plastic like it'll anchor him to the spot. There's no way Dean doesn't know
that he's hard, not with the way he's stretching his lips along the pale line
of Sam's throat and snaking his tongue out as he levels a hooded stare at Cas.
Cas feels the cold seeping into his fingers, doing nothing to counteract the
throbbing heat in his cock.
 
Sam starts a little as Dean murmurs something in his ear. It's too soft for Cas
to hear, but it must have been about him because Sam stands up and stares right
at him. Dean tugs his sweatpants down quickly, letting Sam's stiffy spring free
against his stomach.
 
Cas feels some intellectual part of himself put up a perfunctory protest,
valiantly failing to tell him that he should feel bad, that the sight of Sam's
soft, smooth body and his stiff little dick shouldn't make Cas' stomach do
backflips or make his cock bead up an eager little pearl of pre-come that soaks
into his flannel pajama bottoms like a guilty tear. All Cas can see is the
display of this, that Dean is showing him something, sharing something, and Sam
is in on it and everything feels dizzy and hot despite the chill in the air.
 
Sam's hair is in his face like it always it, dishwater brown framing his eyes
as he looks up at Cas. His mouth is open, his lips pink and sweet and still
thin, not the swollen fuchsia that they plump up to after he wanders out of his
bedroom looking sated and dazed, Dean trailing lazily behind him. Sam is giving
him that same look that's puzzled Cas for days, knowing and quizzical all at
the same time.
 
It's not the wide-eyed look of wonderment that Cas had caught through the crack
of Dean's door, the look Sam had given him as he watched Cas ride his brother
until Dean clenched up under him and came with his fingernails digging into
Cas' hip. That was one of their secrets, the little glimpse Cas had made sure
to give him when he'd bent down to kiss Dean and let it trail out of him. He'd
envied Sam's voyeurism as much as he'd enjoyed Dean's attention to his mouth,
and he was almost sad Sam had left by the time he slid off Dean to lay on his
back and spread his legs. Sam had missed the best part.
 
There's something different in Sam's eyes now, a sort of self-consciousness
that makes Cas' hands itch to go to him, stroke him all over and tell him he's
perfect, that he's loved and he's Dean's and he doesn't need anything else.
Instead Cas just strangles the coke in his hand and watches breathlessly as
Dean urges Sam back onto his lap, spreading his legs to splay them over Dean's.
 
Sam arches his head back, making the delicate cords on his neck stand out as he
leans back to kiss Dean. Cas can see their tongues swirling together, Sam's
small and pink against the thicker red of Dean's. Cas' own groan startles him;
he doesn't even realize he's grinding the bottom of his soda bottle against his
dick until he feels a twinge in his balls.
 
Dean's hand is back over Sam's dick, slowly stroking it up and down. It
shouldn't surprise him that Sam is uncut just like Dean, but it still
mesmerizes him to watch the soft slide of his foreskin over the slick, soft
head of his dick, flushed deep pink just like his lips after he kisses Dean. He
jumps when Dean says his name, repeating it as Cas' throat tries to swallow and
groan and speak all at once.
 
“C'mere, Cas.” Despite the invitation Cas feels frozen on the spot, unsure of
what he's actually supposed to do. Words have never been his strong suit, and
he wouldn't know what to ask even if he tried to speak.
 
“It's ok, Cas, c'mon.” Sam eyes are half-open, and they narrow even more when
he smiles lazily. He looks foxy and flushed and fucking hot and Cas' dick is
tenting his pants so much it would be embarrassing if he gave a shit. Cas can't
resist any more, no amount of awkward could keep him away as Dean reaches a
hand out for him and licks a slow stripe up the side of Sam's neck.
 
Dean's open hand fists into his t-shirt, pulling him down until Cas falls to
his knees beside Dean. He closes his eyes and breathes in deeply. He's close
enough that he can smell them together, that scent that he usually recognizes
as the faint trace of Sam magnified a thousand times.
 
“Wanna do something for me, Cas?” Cas can feel Dean's breath against his face,
hot and damp. He nods and opens his eyes, pleased to see Dean leaning down to
kiss him. Dean's mouth is warm and soft, bearing the faintest taste of Sam like
it has so many times before.
 
“Want you to suck Sammy off, Cas, know you're good at it.” Dean's smirk is all
filthy praise, like Cas has passed a test or leveled up under Dean's guidance.
Cas feels it wash over him, euphoric and buzzing as he turns to meet Sam's
tilted-back face.
 
“C'mon, Cas, I want you to.” Sam licks his lips after he says it, that pink
swipe of tongue jittering right up Cas' spine.
 
Cas' hand flies down to his dick of its own accord, grinding his palm down once
it lands to stave himself off. Cas probably had more sex than any 16-year-old
weirdo on earth but this was the kind of shit he secretly jerked off to.
 
He shuffles over on his knees, awkward if he stopped to think about it but
right now the only thoughts running through his mind are Sam's sweet little
cock on his lips and Dean's firm hands in his hair. And fuck if that's just
what he gets, happy for the hand still pressed against his balls because it's a
thousand times better than his best soap-slick bathroom conjecture.
 
“That's right, all the way,” like Dean has to tell him, like it's even hard
when he's used to calming himself and swallowing Dean's thick length in one go
to earn that approving groan that lit him up inside. Cas' moan as Dean rakes a
hand through his unruly mop of hair is echoed back by Sam, higher and reedier
as his little hips jump forward.
 
Sam tastes different, sweeter and soapier than Dean's earthy-salt-sweat skin,
and there's less pre-come for him to taste as he swipes his tongue through the
small slit of Sam's cock. Sam gasps at that, so Cas does it a few more times,
pulling off to flick his tongue right against it before he takes Sam to the
base again. It only takes a few more passes before Sam's smooth little nuts
draw up even higher and tighter, his stomach muscles twitching as he digs his
hands into Dean's knees.
 
“Fuck, m'gonna, Cas, Dean, oh god, fuck, fuck, guh,” and Cas appreciates the
warning even if he already knows what to do before Dean gives his hair a gentle
tug and barks out a deep, “Don't.”
 
As if Cas would swallow when Sam came. Dean likes his own so much it only
figures he'd want his little brother's fed back to him.
 
Cas usually has to swallow some of it just to keep his mouth closed, but Sam's
little spurt rests easy on his tongue as he rears up on his knees to meet
Dean's mouth over Sam's shoulder. Dean's groan is deep and wrecked, backed up
by the moaning sighs Sam lets out as he slinks off Dean's lap and settles on
his knees next to Cas. For a while the only sounds in the room are the wet
sucking noises Dean makes as he licks the taste of his brother out of Cas'
mouth, claiming it back as his own as if there were any question that they were
both Dean's.
 
Cas jerks as he feels an unfamiliar hand reach into the drawstring waist of his
pants, smaller and softer than Dean's rough grip. “Oh god, Sam,” Cas groans,
knowing he's not going to last long as Sam starts to jack his dick like he's
done it a thousand times before, which, fuck, that image isn't helping him
fight the galloping rush of his orgasm.
 
“That's my boy, Sammy,” Dean huffs out, looking down and smiling as he fists
his own cock, leaking wet at the tip and only adding to the visual overload
thrumming down Cas' spinal column. “Gotta reciprocate, right?”
 
And that's just fucking it, that Dean taught him this, that they'd talked about
it and let him in and let him touch and taste and fuckfuckfuck.
 
Cas comes with a long, high noise, wordless and choked out as Sam flicks his
wrist and works him through it until it's just too much too good don't stop.
 
He's still dizzy and star-struck as Dean pulls Sam's hand off him, shiny white
ropes of come dripping down over his delicate wrist. Cas watches through hazy,
pupil-blown double vision as Dean pulls it halfway to his mouth, tongue snaking
out before Sam jerks it back, his eyes set on Dean's in something challenging
and rivalrous as he brings his hand back to his own mouth. He keeps his
rebellious gaze locked on Dean's as he opens his mouth wide and licks a flat
swipe up the side of his wrist, gathering a pool of Cas' come as he tracks up
to suck it off a fingertip and swallow noisily.
 
Cas groans pathetically and he's not ashamed of it, not when Sam does it again
and Dean just starts gibbering out a stream of curse words and jerking his cock
so quickly Cas would swear the only thing holding him up is the audible chorus
of sucks and squelches and sweat-slick slaps of skin on skin.
 
It's Sam's name when Dean comes, punched out and filtered through gritted teeth
and a cupped hand under the head of his dick. Cas knows his cue when he sees
it, bending down to lap at the hot pool of spunk in Dean's hand before he's
even finished coming. Dean won't mind getting an errant stripe on Cas' face.
 
He's still got sticky-salt Dean on his tongue when Sam sidles up next to him,
running his hot little hands up Cas' ribs and pulling him closer until they're
knee-to-knee, Sam's soft little dick pressing against his thigh.
 
“Dean,” Sam asks, looking up at Dean with wide-eyed expression Cas has seen him
use to great effect on teachers, parents and, most of all, Dean. “Can I kiss
Cas?”
 
Dean swallows and licks his lips, blowing a breath out before he draws the
corner of his mouth up in a smile and nods. “Yeah, baby boy, wanna kiss him
while he tastes like me, huh?” Sam smiles back before he pulls Cas down, his
hand gripping into Cas' hair, and fuck, he definitely learned that from his
brother, although the similarities end there.
 
If Dean is all lips and teasing little nips of his teeth, Sam is tongue, tongue
and more tongue. He licks into Cas' mouth, strong and sure and sweet and fuck,
Cas can't even tell who tastes like who at this point, all three of them
mingled salty and wet and stuck together forever.
 
Cas almost collapses onto the couch, feeling like his heart is going to beat
out of his chest if he stops to think too hard. Instead he just leans his head
against Dean's shoulder, smelling his skin and wriggling around to make room
for Sam's bony ass in between them.
 
“Next time,” Sam says, looking up at Dean as he settles his side against Cas,
“I think Cas should suck me off while you have your finger up my ass.”
 
The look on Dean's face is truly priceless, and it's even better when they
actually do it.
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