Warnings: age difference (Dean is 40, Sam is a temporarily de-aged 18); Dean has a serious underage kink; incest; bottom Sam; established relationship
Summary: Sam finds a de-aging potion in the bunker storage rooms. When Dean reveals that he first fell for Sam the summer before he left for Stanford, Sam decides to use the potion to turn himself into his nubile young 18-year-old self so the Winchesters can both revisit that lost summer of mutual pining.
Link to fic: A03 | LJ
A/N: The idea for this fic came up in a Discord discussion recently. I don’t remember which one or who to thank for this, but the prompt was something about how Dean would love it if Sam could de-age to that nubile young man who left for Stanford all those years ago.
Dean turns over, flicks the light on because Sam’s voice sounds wrong. It’s just... Wrong.
Sam stands in the doorway, slumped over in a hoodie, hair spilling over his forehead, curling around his ears and collar.
He’s... Young. Sheepish. Stubborn and stupid and reckless and... Young.
“What’s going on? What...” What happened to you? is on the tip of Dean’s tongue, but it doesn’t quite come out.
“Can I come in?”
Even his voice sounds young. Hopeful.
“Yeah,” Dean rubs his eyes, sits up. “Did you find some kind of cloaking spell? You look funny.”
Sam blushes as he grins bashfully, dimples cratering his soft cheeks. “De-aging potion, actually.”
Dean sits up straight, frowning. “Like the stuff that witch used on me?” Dean shivers with revulsion. “Why would you mess with that stuff?”
“Because of what you said yesterday.” Sam ducks his head, looks up at Dean from under his bangs. “About how you always wished we could’ve started earlier. How I drove you crazy when I was eighteen.”
Now it’s Dean’s turn to blush. Sam did drive him crazy when he was eighteen. That summer before he left for Stanford, Dean wanted his brother so bad it felt like his skin was burning from the inside out. It felt like fire ants were crawling and biting right under the surface, making him hard and shaky and constantly on the edge of spontaneous combustion.
“Oh for God’s sake, Sam! I didn’t mean you had to — I mean, why would you — “ Dean’s on the edge of the bed, alert and ready to run.
Sam’s taking his clothes off, which is so unfair. His chest is smooth and hairless, long, lanky arms tight and defined with new muscle. Hipbones and elbows jut out from his too-tall-too-fast frame. He’s slender but not skinny.
“It’s okay,” Sam assures him as he toes off his sneakers, pushes his jeans and boxers down his long, long legs. “It wears off in a few hours.”
“Sammy.” Dean’s breath catches as Sam straightens up, stands tall and naked as the day he was born, arms akimbo.
“Okay?” He asks, grinning as Dean’s eyes sweep over Sam’s body, taking in his youthful beauty with hungry admiration. “Like what you see?”
“God, yes,” Dean gasps. “But you’re always beautiful to me, Sam. You didn’t have to do this to get me to say that.”
“Maybe I did, maybe I didn’t,” Sam says with a smirk. He saunters closer, hips swaying, till he steps right up between Dean’s knees.
Dean shuts his eyes, swallows hard, breathes through his mouth because the smell of young, sweaty Sammy is overwhelming. Memories flood to the forefront from the summer all those years ago. Memories of Sam’s golden-brown sun-kissed skin, slick with sweat and dripping from the pool.
That stupid pool. Why did Dad have to leave them at a motel with a fucking pool that summer?
“Dean.” Dean’s eyes blink open. Sam’s bare chest is right there, nipples dark and pebbled. “Touch me. It’s okay.”
Dean huffs out a breath, gets another memory flash of Sam’s long legs in the too-tight, too-short shorts and tank top he wore all the time that summer. Both used to belong to Dean and were too small on Sam, who had just managed to grow over Dean’s head for the first time.
When he walked around without the tank top, in nothing but those shorts, it made Dean’s mouth water.
Dean leans forward, places a wet, sloppy kiss on Sam’s sternum. Memories flood back, colliding with the present. Sam’s skin tastes at once familiar and different. Dean wraps his arms around Sam’s slender torso, shivers as Sam slides his fingers into Dean’s hair and moans. Dean wraps his lips around Sam’s left nipple, sucks hard.
Sam gasps, bucks up into Dean’s mouth. His fingers scrabble and clutch at Dean’s neck, his shoulder, the back of his head.
Dean lets Sam’s nipple go with a smack, kisses across his chest to the other one, gives it the same treatment. The muscle of Sam’s pec fills Dean’s mouth almost like a woman’s breast, the skin just as smooth. Sam’s body was more feminine at this age, Dean realizes with a shock. Smoother, softer, less hairy than the fully adult man he later became.
He doesn’t know what it means that he was attracted to Sam when he was so young, but he thinks it’s probably nothing good.
And now Sam’s letting him indulge in his weird fetish like it’s something Sam wants, too.
They’re both so screwed in the head.
Sam wiggles his ass back into Dean’s hands as he slides them down Sam’s back to his perfect, round ass. He spreads his legs so Dean can slide his fingers into Sam’s crack. When he finds Sam’s hole, he gasps.
“You opened yourself up for me,” he breathes against Sam’s smooth, warm skin. He looks up as he slides the tip of a finger into Sam’s sticky, loose hole. “Such a little slut.”
Sam throws his head back, squeezes his eyes shut as he bites his bottom lip, whines. Dean knows that look. Sam’s trying not to come, just from Dean’s finger in his hole. Just from Dean looking up at him and smirking, just from calling it like it is.
“I would’ve let you fuck me that summer,” Sam breathes. “I wanted it, too. But I thought you’d never.”
Dean rises to his feet, gathers Sam into his arms, and pulls his head down so he can kiss him. Sam’s face is baby-smooth. He’s barely shaving. Dean remembers how excited Sam was to start shaving, how Dean teased him because he really didn’t have enough to shave. His cheeks are soft, just the barest stubble on his chin and over his top lip, and kissing him feels positively illegal.
“Get on the bed,” Dean growls when he finally lets Sam’s mouth go.
Sam scrambles to obey, spreading himself out on Dean’s bed like the hottest twink pornstar that ever lived. His cock lies hard and leaking against his belly, his barely filled-out chest heaves. He tips his head back, exposing his neck, the cleft in his chin, those goddamn moles like a constellation of Dean’s darkest desires. His hair splashes over the pillow as he tosses his head, gives Dean a view of his profile, his perfectly pointed nose and high cheekbones.
“So hot like this, Sammy,” Dean murmurs. “Pull your legs back. Let me see you.”
Sam wraps his long fingers behind his knees and does as he’s told, giving Dean a good view of his tight little hole, glistening with lube.
“Fuck me, Dean, come on.” Even Sam’s voice sounds younger, breathier. Dean’s reminded of the whiny, demanding brat he adored so much when they were young, and it makes Dean’s dick throb.
What a sick, perverted monster he was back then. Still is, for getting off on memories of his little brother when he was so young. It’s only a bitter kind of consolation that he didn’t act on his lust in those days. Wanting his little brother and hating himself for it is a deep part of Dean’s psychology. He’ll never be able to forgive himself for it, even all these years later, even long after Sam’s consented to this. It’s Dean’s fault for destroying Sam’s innocence, for making him fall in love with Dean, however unwittingly. All of Sam’s dirty-bad-wrong feelings for his brother are Dean’s fault.
“Dean, please!” Sam whines and bucks up, wiggles and squirms and touches himself. “Come on!”
Dean’s jaw tightens. He yanks his t-shirt off, shoves his boxers down and kicks them off, climbs onto the bed between Sam’s spread knees. He bats Sam’s hands away, replaces them with his own, shoving a finger into Sam’s ass as he grips Sam’s cock with the other, strokes it with the sure confidence of a lover who’s done this a million times.
Sam moans, low and needy. Filthy. He pulls his knees back, tips his chin up, neck and arms straining with effort.
“Come on, Dean! Hurray up! Need you in me.”
Dean chuckles. “Such a bossy little bitch.” He adds another finger, then a third, determined to make it feel good when he gets his dick up in there.
It occurs to Dean that this body might be a virgin. Sam experimented in college, had Jessica peg him, so by the time he and Dean finally did this, Dean’s dick wasn’t the first Sam had had. And of course Dean was all right with that, even if it made him jealous to think of anyone else touching his Sammy.
But the thought of being Sam’s first makes something low and hot clench tight in Dean’s belly. Makes his dick leak.
“That’s enough, Dean, I’m ready!” Sam whines, bearing down on Dean’s hand.
“Such an impatient little bitch,” Dean growls as he pulls his fingers out, lines up his cock. “Look at me.”
Sam’s eyes slide open, just narrow slits that look almost completely black. As Dean pushes past Sam’s rim, they both gasp. Dean stops, holds himself still to let Sam adjust, to keep himself from going off like a rocket at the sight and feel of his cockhead inside this jailbait version of his brother.
“Dean!” Sam bears down, and Dean slides in to the hilt.
“Son of a bitch!”
Dean sucks in a breath, leans down to bury his face in Sam’s neck, trapping Sam’s dick between their bellies.
Sam starts wiggling again, obviously trying to get some friction for his dick.
“Hang on a minute,” Dean gasps. The tight heat of Sam’s channel clenched around his dick is almost too much. He’s going to lose it if he doesn’t get Sam to hold still.
Sam wraps his legs around Dean’s waist, digs his heels into the small of Dean’s back, and scratches his fingernails along Dean’s skin.
“Come on, Dean, come on!”
Dean takes a deep breath, forces himself to think about dead puppies so he can pull back, then drive back into Sam’s tight hole. He gets a steady pace going, watching as Sam’s face softens into that blissful expression it gets when he’s getting a real good dicking. Sam’s eyes are almost closed, his lips are parted, cheeks flushed, hair mussed. His smooth, bare chest gleams with sweat.
Dean wonders how Sam can sweat when Dean’s the one doing the fucking.
“I should make you bottom from the top,” Dean grunts as he increases his pace until he’s pistoning his hips. “Look at you, all young and energetic. I must be twice your age at least!”
And that’s the thought that sends him over the edge. He comes so hard he’s almost doesn’t notice that Sam’s coming, too, jerking himself hard and fast as Dean grunts and gasps out his orgasm. At the sight of Sam’s white spunk against his brown belly and chest, Dean’s dick gives a final valiant twitch.
“Aw you pretty, pretty boy,” Dean says as he rolls off, hissing as his dick slips free from Sam’s warm body.
They lie side by side, breathing hard. When Dean turns his head, Sam does the same, grins wide, dimples carving his smooth cheeks.
“How was that, huh?” Sam asks. “Did you get your underage kinks out?”
Dean frowns. “Thought you said you were eighteen,” he accuses,
Sam throws his head back and laughs. It’s a sound Dean hasn’t heard in years.
“Whatever.” Dean rolls over, grabs Sam’s shirt off the floor, drops it on his belly. “If you’re planning on falling asleep in my bed, you better clean yourself off first.”
As Sam wipes, he asks, “Was it good? Was it what you thought it would be like?”
Dean knows that tone, even in that much younger voice. Sam’s insecurity’s showing. He’s worried that Dean likes him better this way.
“Yeah, Sammy, it was great. You’re a gorgeous eighteen-year-old.” Dean flips the light off, settles down on the bed on his back. Sam scoots closer, sliding a long arm across Dean’s chest, tucking a long leg between both of Dean’s, laying his head on Dean’s chest so that Dean has to put an arm around him, stroke his thumb along Sam’s shoulder.
“You’re also a gorgeous 36-year-old.”
Sam huffs out a breath that sounds almost like relief. Dean tucks his face down, into Sam’s sweaty hair, leaves a kiss there.
“Truth be told, I’m kinda looking forward to having my older little brother back.”
Sam smiles against Dean’s chest, tightens his hold.
Dean’ll never understand why Sam loves him, but he’ll always be grateful that he does.
When they wake up the next morning, Sam’s 36 again, and the sex is just as awesome.
Having a witch for a little brother does have its perks.