unfaithful
one-shot
Pairing: Demon!Dean x Sam's Girlfriend!Reader
Summary: It's been the same almost every night since Dean left. You wander the halls of the bunker, feet always carrying you to his closed door. Only tonight? It's open.
Warnings: 18+!, language, angst, cheating, mocking, guilt, pining, smut (dirty talk, clitoral stimulation, fingering, p in v, ass-play kinda, gagging), I think that's all.
Word Count: 4,410
It starts with silence. The kind that swells in old, haunted places—thick with ghosts, thicker still with the things left unsaid.
The bunker was never quiet when Dean was alive. Even asleep, he filled the space—snoring down the hall, boots echoing off stone, laughter ricocheting off walls like a warm, familiar gunshot. But now? Now it's just Sam.
Sam and the weight of all that's missing.
He sleeps restlessly beside you, long limbs tangled in the sheets, one arm slung over your stomach like it's instinct. You've been his anchor for years, since before Lucifer, before Ruby, before the bunker was even carved into your lives. His grief is a living thing now—tucked into his spine, sewn into the dark crescents under his eyes. He doesn't cry. Sam doesn't do that. He burns. Quietly. Patiently. Like a fuse with nowhere to go.
And you love him. God, you do.
You love the way he softens when you brush his hair back. The way his voice cracks when he says your name like it still means safety. The way his fingers find yours in the dark, like maybe you can hold each other together.
But you haven't been sleeping. Not since Dean. Not really.
Because love isn't always enough to quiet the hum beneath your skin. The one that started when the bunker went still. When Dean's door slammed shut. When Sam stopped saying his name with any emotion because the syllable hurt too much on his tongue.
It's been a couple months, maybe more, since Dean disappeared. Since the Mark swallowed him whole and left Sam behind to dig through the wreckage.
He won't call it that. Disappeared. He says gone, like he's coming back. Like he's late, not lost.
But every time Sam leaves to follow another lead—a demon sighting here, a body drained dry there—he comes back heavier. Shoulders hunched. Jaw clenched. A little more wrecked than the time before.
The last time, he came through the war room doors with his arm in a sling and blood crusted in his hair. He wouldn't look at you when you pressed your hands to his chest and asked what happened. Just muttered something about a crossroads deal gone sideways and that he "got what he needed."
You didn't ask what that meant. Not because you didn't want to know. Because you weren't sure you could carry it.
So you kissed his temple and made him tea and sat beside him in bed, letting his weight lean into yours until the tension bled out of his body. He was asleep in minutes.
He always sleeps when he's home now. And you? You stay awake.
Because when he's gone, the bunker is all stone and silence and the sound of your own spiralling thoughts. And when he's here, it's somehow worse. Because you can feel how far away he is—even with his arm around you, even with his head on your chest.
He used to laugh more. God, he used to laugh.
Now, he only talks about Dean. His voice tight. Raw. Like the name alone is a wound.
And you love him. You love him with everything you are. But love doesn't keep the walls from closing in. It doesn't stop your skin from prickling every time you pass Dean's room. It doesn't erase the way your heart beat different when Dean was still here—messy and loud and impossible.
It just makes you feel worse for noticing.
You don't mean to get up. You try, god, you try to just lie there, listening to the slow, steady rhythm of Sam's breathing beside you—soft and even, his body warm under the blankets, pressed into your side like he knows the second you leave, he'll feel it.
But still, you slide out from under his arm like a ghost. Still, you pull his flannel off the back of the chair and slip it over your bare shoulders. Still, you pad barefoot across the bunker floor, silent and aching, like something inside you is pacing the walls of your ribcage.
It's not that you're not tired. It's that you can't rest. Not with all this noise inside your head.
You make your rounds like you always do—through the library, past the war room. Everything's dim, quiet, lit only by the soft golden wash of overhead lamps left on low. Books you've already read sit open-faced on the table. A mug of tea long gone cold. Nothing helps.
Your feet move on their own. They always do. And you know where they're taking you. You always know.
Past the weapons room. Past the corridor where the lights flicker just a little when you breathe too hard. And then—
There it is.
Dean's door. Always shut, still sealed like a tomb. Except tonight, it's not. It's cracked open, just barely. Just enough.
You stop in your tracks, throat going tight. Your heart pounds like it's got something to say—but you don't want to hear it. You should go back to bed. You should lie down with Sam and pretend you didn't notice. Pretend you don't always end up here, standing in front of the last place Dean touched.
But the truth is...
You were always going to stop.
Even when he was alive, there was something about Dean that pulled you off course. Something gravitational. It wasn't like it was with Sam—steady, soft, true. Dean was a fire you kept your hands from, even when your skin ached for the burn.
You never said it out loud. Not even to yourself. Because to name it would've been to shatter everything you'd built. And you loved Sam. You still do. That's the worst part.
But Dean... Dean was something else entirely.
Something dark and sharp-edged and dangerous. Something you only let yourself want in your dreams—the kind that leave you waking up gasping, thighs clenched, shame curling in your gut like smoke.
You thought the ache would die with him. You thought grief would overwrite the hunger. But here you are, standing in front of his door again.
And tonight, it's open.
Your hand moves before your mind can catch up. Fingertips against wood. A breath held in your throat. The door groans quietly as it opens wider beneath your touch.
And he's there. Standing in the middle of the room like he never left.
Dean.
But not.
His hair is perfect, of course—flawless in that infuriating, tousled way like he rolled out of bed smug. His skin is golden under the low light, his jaw shadowed with stubble. A tight red shirt clings to him like a second skin, sleeves rolled to his elbows, forearms flexed like he's waiting for something.
But it's the look on his face that stops your heart dead in your chest. That grin. That slow, smug, shit-eating grin. It's Dean, and it isn't. His eyes are darker. Not black, but close—gleaming with something feral. Something cruel.
And he's leering at you. At your bare legs. At the way you're clutching Sam's flannel closed around your body like it's armour. Like it's going to protect you from him.
"Lookin' for me, sweetheart?"
His voice is a low drawl, thicker than you remember, honey poured over poison.
You can't move. Can't speak. You just... gawk at him.
Because what the fuck?
Sam has been tearing the earth apart looking for him. Nearly died chasing after scraps and whispers and demon tracks. He's got a sling on his arm and bruises he doesn't talk about and a look in his eyes like something inside him is breaking, and—
And Dean's just here. Standing in his room like it's a Tuesday. Looking you over like you're dinner. Like he's already decided how this ends.
"Cat got your tongue?" He murmurs, cocking his head, eyes dragging slowly down your body. "That mine?" He adds, chin-jerking toward the flannel you've pulled tight over your chest. "Or Sam's?"
You swallow hard, voice lost somewhere between your ribs and your gut.
He steps forward. One slow stride. Then another. And the closer he gets, the clearer it becomes—this isn't the Dean you remember.
This Dean doesn't carry guilt like a second skin. He's not breaking apart under the weight of his choices. No—this Dean is whole. Whole and dark and dangerous. And from the way he's looking at you now? He's starving.
Your voice slips out of you like it's been trapped behind your teeth for weeks.
"...Dean?"
He exhales like you just gave him life. His eyes flutter closed for a second, jaw flexing, that awful, beautiful grin widening.
"Fuck," he whispers, almost to himself. "There's that voice I missed."
When he opens his eyes again, they're molten. A furnace. Locked on you.
"You have any idea how many times I imagined you saying my name just like that?" He says, low and lazy, taking another step closer. "'Cept maybe you're on your knees. Maybe you're spread over Baby's hood. Or—fuck, maybe you're sittin' right in Sam's lap while I'm—"
"Dean."
It comes out more like a warning than anything else, but your grip on the flannel tightens. Your knuckles are white.
"What the hell is going on?" You whisper, pulse pounding in your throat. "You're alive? Where the—how are you here? Sam's been—he's been looking for you, he's been—"
"Oh, I know," Dean cuts in, eyes glittering. "Sammy's been very busy. Playing hero, getting himself all bruised up just for little old me." He steps close enough now that you can smell him—soap, leather, whiskey, and something wrong. Something deep and sulphurous beneath the surface. "And where's his sweet little girlfriend while he's out savin' the world?"
You don't answer. Can't.
Dean's gaze drops to your mouth. Lingers there. Then drags slowly back up.
"Home alone. Wrapped up in his flannel. Lookin' like a fuckin' gift."
"Dean, stop—"
"Why?" He murmurs, cocking his head. "You're standing in my doorway, baby. Wearing his shirt but lookin' at me like you wanna drop it and let me ruin you right here."
You stumble back a step, but he follows, slow, stalking. A predator playing with his food.
"I mean, shit," he drawls. "You don't think I noticed how you looked at me back then? All those years? You were so good, weren't you? Loyal little thing. Always kept your legs crossed, always trying to keep your eyes on Sam."
He steps close enough to touch you, but he doesn't. Not yet.
"But I bet you wondered," he whispers, voice like smoke curling around your ears. "Bet you laid awake more than once, wondering what it'd be like to get a taste of the bad brother."
Your breath catches, and Dean smirks.
"Lemme guess. You'd ride Sam's cock like a good girl, but you were thinkin' about me. About how I'd make you beg for it. About how I'd tear you apart and leave you a mess on the sheets. Don't lie. I can see it all over your fuckin' face."
"Dean, stop," you say again, but your voice is thinner this time. Weak. You don't sound convincing, and he knows it.
"Oh, you want me to stop?" He purrs, finally reaching up, brushing your jaw with the backs of his fingers, so gently it makes your knees tremble. "Or you want me to drag you into this room, bend you over that chair, and fuck you like you need it?"
You're shaking. You hate him. You love him. You hate yourself for standing there. And still—
You don't run.
Dean's fingers brush your jaw again, and when you don't flinch—don't recoil, don't run—he grins. That grin. Wicked and slow. Like he knew this would happen eventually.
"Atta girl," he purrs, voice gravel-thick with satisfaction.
Then he grabs you.
Not rough, not yet—but with enough force to make your breath stutter. His hand closes around your wrist, dragging you across the threshold and into the dim, still room that smells like leather and bourbon and the faintest trace of gun oil.
You don't fight him. You should. But your feet move where he leads. Right into the lion's den. And then he glances at the door behind you, fingers tightening ever so slightly on your wrist like he's weighing something. Considering.
Then he looks back at you with a raised brow, lips twitching.
"...Fuck it." He lets the words roll off his tongue like a dare. "The door stays open."
Your heart lurches in your chest.
"What—"
"I wanna see if you can keep that pretty little mouth shut," he says, stepping in close, his breath hot against your cheek. "Wanna know if you can take my cock and not wake Sammy up down the hall. That sound good, sweetheart?"
You shake your head—somewhere between no and I don't know—but he's already walking backward, pulling you with him.
"You really shouldn't be here," he says, faux-regret dripping from his voice. "But fuck me, you look so goddamn good in his shirt. Like you want me to wreck you while you're still wearing it."
He backs up to the desk and spins the chair around behind him.
"C'mon," he murmurs, low and filthy. "Over the chair, baby. Let's get you nice and bent for me."
You hesitate. Just for a second.
But then he tugs the flannel—Sam's flannel—just a little, exposing one shoulder, and hums like he's opening a present.
"Keep it on," he says, voice darker now. Rougher. "I wanna fuck you in his clothes. Wanna ruin you in the last thing he touched."
Your knees hit the chair. His hand is on the back of your neck now, guiding, not forcing—but firm enough you feel your breath stutter.
"Bend over," he whispers. "Hands on the seat. Ass up. That's it."
You're shaking. And he loves it. He kicks your legs apart gently with the side of his boot.
"There we go. Look at that. That's my girl."
You feel the flannel shift as he runs his fingers down your spine. His palm smooths over your ass, slow and proprietary.
"All these years playin' house with Sammy. Being good. Loyal. And all it took was one look at me tonight, and now here you are—wet and desperate and ready to get fucked like the filthy little secret you are."
He leans in, breath at your ear.
"You gonna let me ruin you, baby?"
You break before he even touches you.
Tears spill without warning, hot and fast, sliding down your cheeks as you grip the edge of the chair. Your body's trembling. With shame. With want. With everything you're too afraid to name.
Dean pauses. Then you hear his boots shift behind you. A second later, he's in front of you. Squatting down, one knee bent, his eyes catching yours beneath the curtain of your hair.
"Oh, baby," he coos, voice like silk dragged across a blade. He reaches out, thumb brushing your cheek, swiping away a tear.
Then he brings it to his mouth. Licks it clean.
"Cryin' already?" He murmurs, tilting his head. "That for me, sweetheart? Or for Sammy?"
You sniff, ashamed, eyes closing as another tear rolls free.
"There's no use in cryin'," Dean goes on, softer now. "You're getting what you've wanted for years."
He leans in, kisses the corner of your mouth, feather-light. Then your lips. You melt into it without meaning to. A broken whimper caught in your throat, your whole body pressing forward into the kiss like you need it.
He grins into your mouth. Smug. Knowing. And you hate him for it. But you don't pull away. When he finally draws back, he wipes your other cheek with the pad of his thumb.
"That's my girl," he whispers, and then—he's gone. He circles behind you again, hands dragging slowly down your back. "Flannel still on. Good."
Then you feel it—his fingers sliding beneath your panties, tugging them slowly down your thighs. He catches them just before they fall past your knees, lifts them to his face, inhales.
"Christ," he mutters, voice wrecked for a moment. "You smell like sin."
He folds them up, tucks them into the breast pocket of his red shirt like a souvenir.
"Mine now."
You whimper again, and he hums, pleased. A belt clinks open. Denim rustles a fraction. And then he's back—kneeling behind you this time. His hands spread your thighs wider, and then—
Oh god.
He sniffs you.
Right at the crease of your thigh, slow and obscene. Then his tongue drags a stripe up, hot and deliberate, until he's right at your centre.
He moans.
"Fuck."
Another kiss, soft and maddening, pressed to your clit like worship.
"You have no idea," he breathes against you. "How many nights I used to lie awake in that bed..."
He presses a finger inside. Slow. Deep. You choke on a gasp.
"...jerkin' myself raw, thinking about this pussy. About how sweet you'd sound begging me to ruin you."
The finger curls. You cry out—too loud—and he growls.
"Shhh. You wanna wake him up? Huh?"
You shake your head, clutching the chair like it's the only thing anchoring you to the earth.
"I'd come back from hunts all wound up and pissed off," he continues, voice ragged. "And you'd be there—wearin' your little shorts, leaning over the table with your mouth all smart and your ass lookin' like sin. And I'd be thinking about what you sound like when you come. How tight you'd feel clenching around my cock. What kinda mess you'd make."
He slips a second finger in. You cry out again—quieter this time. More desperate.
He grins against your thigh.
"Bet Sammy's never even made you come like this, huh?"
Dean's fingers pump into you slow and steady—just enough to make your thighs shake, but not enough to push you over. You bite your lip to hold back the sounds, forehead pressed to the seat of the chair, breath fogging the leather.
"You wanna wake him up?" Dean mutters, his voice low and tight as his fingers curl just right. "You wanna hear him walk down that hall and see you spread for me like a fuckin' whore?"
You gasp. Whimper. Shake your head.
"Didn't think so," he huffs. "Then keep your goddamn voice down."
He thrusts his fingers deeper, scissoring them inside you, tongue dragging along your inner thigh again like he's starved.
"Son of a bitch," he groans. "You're tight."
He fucks you with his hand like he means it, wet and obscene, the sound of it echoing off the stone walls of the bunker like a crime.
"Holy crap," he breathes out. "This is even better than I imagined. And trust me, sweetheart—I imagined it a lot."
He grazes your clit with his thumb, just a whisper of contact, and your whole body jolts.
"Shit, look at you," he laughs. "So fucking desperate. So goddamn wet for me. And in his shirt, too. That's real cute."
Your legs are trembling. You can feel it coiling in your belly—that tight, unbearable pressure.
You're gonna come.
"Dean—please—"
"Oh no, sweetheart," he cuts in, voice going sharp as he slows his pace to a crawl. "You don't get to come yet. Not unless you tell me what I wanna hear."
You shake your head, gasping. "What—what do you mean—?"
He leans in, lips brushing your ear, fingers curling inside you with cruel precision.
"You don't come," he says, low and commanding, "until you tell me you love me."
You freeze.
"Go on," he murmurs, breath hot. "Say it. Say you love me. Say it like you mean it."
"I—I can't—"
"Then I stop," he shrugs, withdrawing his fingers with a slick, obscene sound. You cry out, body clenching around nothing, so close you could scream.
"You don't wanna come that bad?" He taunts. "Guess I overestimated you."
"No," you breathe, desperate, eyes stinging again. "Please—please, Dean—"
"You think Sam would make you beg like this?" He growls, grinding his cock against your ass now through his boxers. "You think he'd know how to ruin you right? Like this?"
You moan, the friction almost enough to tip you over again, but not quite.
"Then say it."
He grips your hips hard, hissing under his breath. "Say you love me or I'm leaving you right here dripping and empty."
And you break.
"I love you," you sob. "Dean—I love you."
There's a beat of silence. Then—snap. His belt hits the floor.
"That's my fuckin' girl."
He's kicking his jeans off, tearing his boxers down, and then his cock is pressing against your soaked entrance, thick and hot and so fucking wrong.
He pushes in slow. Deliberate. Every inch feels like a sin you can't take back.
"Holy shit," he groans. "You really are tight."
You bury your face into the seat, choking on a cry, your entire body shaking.
"Take it," Dean hisses, hips rolling as he bottoms out. "Take all of it, baby. Fuckin' feel me."
He starts moving—hard and slow and deep. The chair rocks beneath you with every thrust, the open door behind you reminding you exactly how close this secret is to shattering.
"You feel that?" He pants. "Feel how deep I am? That's where I belong. That's mine. Always has been."
You're moaning now, helpless, face streaked with tears and pleasure.
"You keep clenching like that," he grits out, "I'm not gonna last long."
His hand tangles in your hair, pulling your head back as he thrusts into you harder, meaner.
"Bet you think about this every night now," he snarls. "Bet you go back to his bed with my cum dripping down your thighs and pretend you're still a good girl."
You scream into the leather, your body unraveling under his, fire licking up your spine.
"Come for me," he orders, voice raw. "Do it. Let go. Fuckingsay my name."
"Dean," you gasp. "Oh—god, Dean—"
You shatter.
And he doesn't stop.
You're sobbing into the chair now, blabbering incoherent pleas between the aftershocks, your thighs shaking violently as Dean keeps moving inside you—slower now, deeper, like he's savouring the feel of your body spasming around him.
"Fuck," he breathes, sweat beading at his temple, one hand still tangled in your hair, the other gripping your hip hard enough to bruise. "Look at you. Wrecked. Can't even talk right, can you?"
You let out a broken noise—somewhere between a whine and a sob.
He chuckles darkly. "Didn't think I'd fuck you stupid this fast."
His hand slides up, reaching into the pocket of his shirt—your panties, still warm from being tucked against his skin. He pulls them out, dangles them in front of your tear-soaked face like a prize.
"As much as I love these pretty little sounds," he murmurs, mocking sweetness dripping from every word, "I ain't ready for Sammy to come wanderin' in here asking why his girlfriend's whining like she's never had cock in her life."
He stuffs the panties into your mouth, slow and deliberate, pressing them past your lips with two fingers.
"There we go," he coos. "That's better. Nice and quiet."
You gag around the fabric, drooling, tears still leaking from the corners of your eyes—and Dean groans, hips stuttering at the sight.
"Jesus Christ, you look so good like this. Stuffed full'a me, mouth full of your own shame. Fuckin' perfect."
Then—he slows. Just a beat. Just enough to lean down and really ruin you.
One hand snakes between your cheeks, thumb pressing just under your tailbone, circling—until—
You jerk, whimpering around the fabric, eyes wide.
Dean laughs, low and cruel and utterly delighted.
"Sensitive, huh?" He murmurs, pressing the pad of his thumb just inside your ass, keeping you right where he wants you. "Don't squirm, sweetheart. Gotta keep you nice and still while I fill you up."
His thrusts pick up again—harder now. Meaner. The wet slap of skin on skin fills the room, echoing off the walls like a fucking dirge.
"Been waitin' years for this," he pants, voice going ragged. "Years of watching you play house with my fucking brother—dressed up like his little good girl, never lookin' twice at me."
Another thrust. Your whole body jolts.
"But I knew. I knew what was underneath. Knew you'd fall apart the second I touched you. And now look at you—soaked, stuffed, fucked out, cryin' into a goddamn chair while Sammy dreams down the hall."
He's getting close. You can feel it. His rhythm falters, hips jerking.
"You're mine now," he growls, biting out the words like a vow. "Don't care how many years you've been with him. Don't care what he means to you. You let me in, baby. That's all I needed."
One more thrust. Two. And then—he groans, low and brutal and satisfied, hips grinding as he comes deep inside you.
He holds you there—panting, trembling, pulsing around him—thumb still snug between your cheeks, panties stuffed in your mouth, Sam's flannel hanging off your shoulders like a scarlet fucking letter.
"Goddamn," he breathes, resting his forehead against your spine for a beat, voice low and reverent now. "Better than I ever fucking dreamed."
He presses a kiss to your shoulder.
"You're not walkin' straight tomorrow," he adds, smug. "But don't worry—I'll be right here to remind you why."
He doesn't pull out right away. Just stays there—buried deep, still twitching inside you, one hand splayed across your lower back, the other slipping up under the flannel to palm your breast with lazy ownership.
The silence is thick. The kind that rings. Your heartbeat is all you can hear—fast, frantic, shame-soaked.
Dean breathes deep, then exhales slow. "...Shit." It's almost fond.
He slides out with a wet sound, groaning under his breath, watching the mess drip from between your thighs with open satisfaction.
"Fucking hell, baby," he murmurs, dragging a finger through it, spreading it with no shame at all. "Can't believe you let me do that. In his shirt."
You whimper, still gagged, still shaking. Your knees nearly give as you try to straighten up.
He catches you by the waist, steadying you effortlessly. Then, softly—mockingly:
"You done crying?"
You don't answer. Can't. Not around the panties in your mouth. But your eyes say everything.
Dean leans in, mouth brushing your ear.
"I want you in my bed next time," he murmurs, voice like velvet and poison. "Naked. On your knees. Beggin' me to do it all over again."
You let out a broken sob—quiet, shameful.
He grins. Stands tall. Tucks himself back into his jeans without taking his eyes off you.
Then—
"But if you're just gonna go crawl back into Sammy's bed and cry yourself to sleep..." He shrugs, flicks his belt shut with one hand. "Might as well run along."
His eyes flick to the door.
"It's still open."
You turn—barely able to walk, face flushed and soaked with tears, the flannel falling off one shoulder. Every step away from him is a scar.
And as you reach the threshold, he calls after you—softly, smugly:
"Don't forget what you just gave up, sweetheart."
Your legs are barely working. You're half-naked, wearing Sam's flannel, marked inside and out by his brother's mouth, his cock, his voice.
The silence chokes you now.
Behind you, Dean drops into his desk chair like a king after war—chest rising and falling, a smirk tugging at his lips as he watches you go. He doesn't say anything else. Doesn't call you back. Just... waits. Because he knows what he's done. He knows what you are now.
You stop in the doorway, one hand on the frame. Look down the hall—toward the room that's supposed to be yours. The bed you share. The man you love.
Then you glance back. At Dean's bed. Unmade. Open. Waiting.
You stay there a second longer—undecided. A trembling silhouette caught between sin and salvation. And the door never shuts.
A/N: Okay, I am well aware of how goddamn cruel this was... but I lowkey don't really care (sorry Sammy bby) because how fucking hot? Ew. Gross levels of hot. Let me know what y'alls think pleaseeee. All the love.
Dean taglist: @mostlymarvelgirl @losers-clvb @lunaleah @itshellfire @drakulana @sl33pylilbunny @suckitands33 @nevercameraready @0ccvltism @bittersweetfig @lyarr24 @podiumackles @spxideyver @tinas111 @paristheonewhoreads @winchestersbgirl @blossomingorchids @sacr1ficialang3l @liiiilsss @mj-102009 @kaz-2y5-spn <3
Also tagging @sorryitsmyfirstdayonearth because I need you to see that I wrote it, please don't sue me. <3

















