A/N: Written for a prompt on tumblr. Hope anon is happy with this!

Warnings: Underage Sam, 18yo Dean, crossdressing (is that a warning? lol)...

Disclaimer: Don't own. Would kill for. That is all.

Sam's frantically searching for his history textbook when he finds it. He holds it up with two fingers, scrunching up his nose and waving it a Dean.

"What is this, and why is it in my duffel?"

Dean looks up from his breakfast. "Hm?" Then he chuckles. "That's a bra, Sammy, you've probably never seen one before."

Sam scowls, "Ha ha very funny. I know what it is. I meant whose? And again, why was it in my duffel?"

"It's Mandy's? Maddy's? Monica's? The smokin' hot cheerleader," Dean explains. Sam gives him a bitchface and chucks Mandy-Maddy-Monica's bra onto the bed. It's pink, with little white hearts and a bow. Sam imagines vaguely what she looked like in it.

Dean imagines in great detail what Sam would look like in it. Then he shakes the thought from his mind. Sam finds his textbook and shoves it in his bag.

"Come on, Dean, we're going to be late for school."

Dean finishes his bagel and grudgingly gets up, willing his dick to behave itself. Sam is fourteen, dammit! He repeats it over and over like a mantra. You can't have sex with your brother.

He leaves the bra on Sam's bed, smirking.

At school Sam sees Mandy-Maddy-Monica in the hall and his ears turn bright red. He ducks into the bathroom and tries desperately not to think about Dean having sex. It's futile. All he ever thinks about is Dean having sex.

Dean having sex with him.

But Dean likes girls. Really likes girls. Mandy-Maddy-Monica was just the latest in a string of… Jesus he'd lost count around forty.

In the bathroom, Sam comes up with a plan. It's ridiculous, ludicrous, and probably going to end with a very embarrassed Sam, but this has gone on for long enough.

That night Sam waits until Dean's in the shower, then he puts his plan into action.

Dean comes out of the shower wrapped in a towel, and his jaw drops. His brain shorts out and his hand goes to the towel to make sure it doesn't fall and reveal his hard-on.

"Sam?" he gawks.

Sam wiggles his hips. "You like?"

He'd made a stop on the way home from school and bought panties to match the bra. Which he's wearing now.

Dean sucks in a breath through his teeth.

"Yeah, Sammy, I do." And he quickly closes the gap between them and presses his body up against Sam's.

Sam freezes. "Wait, really?" He had been prepared for rejection, teasing, disgust, but had never once imagined Dean—kissing him? His eyes go wide at Dean's lips on his. He smiles into the kiss and his hands find their way to Dean's waist. Dean pulls back.

"You don't know how long I've wanted this," he breathes, hands snaking around Sam. His fingertips find the elastic of the panties. "These are cute," he grins, wiggling an eyebrow. Sam turns beet red and Dean drops to his knees, kissing Sam's stomach and trailing his lips down. Sam's impossibly hard as Dean mouths at the pink silk. His legs are shaking, he's being held up by Dean's hands. Sam winds his fingers through Dean's hair and groans as Dean's mouth envelops his bulge. "Mm, baby boy," Dean groans.

"Dean!" he cries as his hips jerk forward. He comes, white hot spurts soaking the panties. He staggers forward, hands on Dean's shoulders for support. Dean kisses Sam's cock and stands up, hugging his brother. Sam pants against his chest, spent.

.

The next night there's a pair of black lace panties and a bustier lying on the bed. Sam puts them on, fumbling with the clasps. He catches sight of himself in the mirror. Slender pale body, toned abs, defined hipbones, rounded ass. His long hair falls over one eye, his lips are pink and full. He looks good. He also looks like a girl.

Dean keys into the motel room and Sam spins around. He puts his hands on his hips.

"What do you think?" he asks.

Dean drops the bag of groceries and rips off his shirt. "Sammy you look hot," he purrs, striding over to Sam. "So sexy, baby boy." And his hands are on Sam's ass, thumbs sliding under the waistband. His cock is hard in his jeans as he grinds against Sam. He kisses Sam on the lips and then uses his teeth to untie the bow on the bustier. He kisses Sam's exposed chest, then back to his lips. Those plump, rosy lips. He bites gently and then nudges Sam down onto his knees.

Sam looks up at Dean through long eyelashes as he undoes Dean's zipper. He licks his lips as he slides Dean's jeans down. Dean's not wearing underwear so his cock springs free, hard and dripping with precum. Sam tentatively leans forward and licks the tip and Dean shivers with excitement.

"Sammy," he hisses as Sam's lips wrap around his cock. "Baby, so good."

Sam swallows as much as he can, bobbing down with Dean's guidance. Sam's lips, his tongue, the way he looks in that outfit, are enough to set Dean over the edge. He pulls out of Sam's mouth as he comes, spilling cum all over Sam's face.

"So beautiful, baby," he moans as Sam licks cum off his lips.

.

The next night there's a red and black corset with matching panties, garters, fishnet stockings, and black heels. Sam's eyes widen. He puts them on with slight difficulty and walks around the room a few times to get used to the heels. He feels like a freak show. Like someone should be stuffing singles down his bra. Fuck, he's wearing a bra.

But this gets him Dean. And Dean is worth it.

He sucks Dean off again, while Dean murmurs praise. Dean leads Sam over to the bed. "You look perfect, baby. So sexy." Sam climbs up on Dean's lap, straddling him.

"Dean…" he starts, then trails off.

"What baby?"

Sam shakes his head. "Nevermind. I love you."

Dean kisses Sam and then flips him on the bed. He slides his panties down and kisses the tip of his cock. "Baby I want—I want to fuck you baby," Dean says, low and guttural.

Sam throws his head back as Dean's tongue grazes over his tight pink hole.

"Yes, Dean, fuck me," he moans.

Dean reaches over to the nightstand for lube and slicks his fingers.

"You ready, beautiful?" he asks, circling his thumb around Sam's hole. Sam trembles and nods. Dean slips one finger inside. "You okay baby?" Sam's so tight. Dean's not sure if he can fit another finger in, much less his cock. Sam grabs the sheets in a deathgrip. His cock is achingly hard and Dean thinks if he just touched it Sam would explode. He works his finger in deeper. Sam writhes on the bed, gasping with pain and pleasure. Dean leans down and sucks at the head of Sam's cock, and Sam bucks wildly, coming hard into Dean's mouth. Dean swallows and laughs. They'd work up to cock.

.

When Sam comes home from school the next day there's an entire outfit laid out for him. Bra and panties, pink tank top, short black skirt with heeled boots. Sam puts it on, but something makes his stomach turn. Dean wasn't turned on by him at all until he put on that bra. Dean only likes him because he looks like a girl. Dean's trying to make him a chick.

He changes back into his jeans and hoodie and waits for Dean.

Dean frowns when he comes in. "Did they not fit?" he asks.

Sam shakes his head.

"What's wrong?" Dean frowns.

Sam chews his lip. "Dean… do you—do you only want me when I look like a girl?"

Dean looks taken aback. "What?"

Sam tries again. "The panties, the clothes, is that what turns you on?" his voice cracks, tears threatening to spill from his eyes.

Dean rushes forward, taking Sam into his arms. "No baby, no. I love you," he strokes Sam's cheek. "I love you so much. Just you looked so beautiful in those panties, that yeah, they turn me on, but Sammy, you're what I really want. Okay?"

Sam nods as Dean wipes away his tears. Dean kisses Sam chastely and pulls away.

"From now on it's just you. No girly clothes, I just want you baby."

Sam looks down, blushing, "Well, I mean, I guess can still wear them sometimes…" he smiles shyly. "I do look pretty hot in them don't I?"