Title: Good Girls Do…
Fandom: Supernatural
Pairing: Dean/Sam
Rating: NC-17
Wordcount: 3021
Spoilers: Set pre-series AU.
Genre/Warnings: AU, mostly PWP, incest, feminization, transexual!Sam, transgender issues, crossdressing, BAMF!Sam, mild violence, bottom!Sam, horny!Dean, explicit sex, bare-backing, schmoop, lap-sex, body-modification.
Summary: Samantha may be a good girl, but she can still kick ass like a Winchester.
Disclaimer: I do not own Supernatural, nor the characters portrayed in this story and I make no profit from these writings.

Samantha looked cautiously around the far corner of the high school gym before stepping out and heading towards the far parking lot where Dean was picking her up. She'd started asking him to come there instead of the main pick-up a week ago when Troy Wethers started lurking around trying to flirt with her. The jock hadn't listened the last month after she had repeatedly told him no when he asked her out and she was starting to get mad.

Troy was the school's senior class president and the quarterback for the football team. He was reasonably attractive and acted as if Samantha should fall to her knees in joy at the chance to be with him. He figured that she was just hot enough to be on his level, but not popular enough to overshadow him in popularity… or at least that's what he told her. Self centered prick.

Since Samantha had started going to Jamieson High School six weeks ago, she'd mostly stayed off the radar of the popular crowd, which was fine with her. She was quiet and kept to herself, always with her head in some random book; she wasn't exactly what kids her age would call cool. But somehow Troy had latched onto her like a pitbull with a death grip… he probably wouldn't be so interested if he knew her secret though.

From an outside point of view, Samantha was a seventeen year old girl. She was 5'6" with long brown wavy locks, large perky breasts, a trim waist, long shapely legs and a curvy backside. Samantha didn't go out of her way to slut it up, but she didn't go the whole nerdy school marm way either. Today's outfit was about norm, she had on a cute a-line demin skirt that hit just above her knees with a white t-shirt and a black cardigan. She usually chose girly, but modest clothes, as a way to keep unwanted attention… and just because she wanted to look like a lady. Even still, though she wasn't vain by any means, she knew she was hot. Boys, and even men lately, had trailed around her for years trying to get her attention… to get between her legs, but she was a proper lady and a one-man-only kind of one at that. Dean was her man and she wouldn't have it any other way.

Now if those boys and men knew exactly what dangled between her legs, they might not be so keen to get a chance to lie between them. Samantha was born in a male body, but in everything that mattered she was a girl. She'd known since she was nine years old that she was a girl on the inside... she was just born in the wrong body. For three years now Samantha had lived as a girl full time and had been taking hormone therapy to bring her outer body in line with her inner mind and slowly but surely it was getting there.

But one little thing still remained… her penis. It would be years before she could have that last obstacle removed, but she had accepted that her journey to womanhood wouldn't be smooth or short. Lucky for her she had Dean to stand beside her throughout it all.

"Hey there sweet thing, when you going to say yes and get with me?"

Samantha froze at the sound of Troy's smarmy voice as she passed the bleachers right before entering the football field's smaller parking lot. She could see Dean standing not too far away, leaning back against the hood of the Impala, with a grin as he waited for her.

With a sigh she turned.

"Troy." For the most part Samantha kept the edge out of her voice, but from the look on his face she didn't think it would last very long.

Standing in front of the Impala, Dean watched as Sammy stopped as one of the school jocks said something to her. The dude had "douche" written all over him, from his perfectly cut and styled hair to his letterman jacket and expensive distressed jeans to his cheesy "I'm rich and hot, so suck my dick" smile.

Most men would get stupidly aggressive and territorial when a guy like that gave that kind of smile to his girl, but Dean wasn't like most guys and Sammy definitely wasn't like most girls. His baby was special under that sweet innocent smile and those proper ladylike clothes, so he leaned back on the hood of his other baby and enjoyed the show.

"… thinking we could go for a…" the jock's voice faded out as he leaned in and spoke to Sammy.

Sammy frowned and leaned back away from him, taking a half step back to put more space between them. Sammy's soft voice was too quiet for Dean to hear, but she had on bitchface #21, the "what the fuck is wrong with you" face, so Dean guessed it wasn't a yes.

Chuckling, Dean heard the jock say "… parents away… jacuzzi with a bottle of… maybe have you suck…" The more the guy talked the more Sammy's face faded from bitchface #21 to bitchface #15, the "give me space right the fuck now or I'll rip off your arm and beat you with it" face.

"… how many times do I have to… no jacuzzi, no… don't like you…" Samantha stepped back and started to turn towards Dean when the guy grabbed her arm and pulled her back against his front and whispered in her ear.

The idiot was looking to get beat. Sammy may look like your average girl, but she wasn't. Besides the whole guy/girl thing, she was a Winchester and Winchester's learned early on how to beat the shit out of anyone who was threat to them.

Sammy hissed something low that didn't quite reach Dean and tried to step away, but the dickwad wasn't getting the hint. He pulled her back to him and tried to cop a feel of her boobs. Big mistake. Whirling around Sammy decked the guy sending him tumbling back against the bleacher wall with a cry.

It was a thing of beauty and had Dean hard in a half second flat. Sammy's chest was heaving, her tits bouncing slightly as she took a few steps back to stay out of the way of any hits the dick might throw at her. Her body was coiled tight in a fighting stance, ready for anything.

"Shit, that's hot." Breathed Dean with a grin.

"… ever touch me again."

"Bitch!" The guy lunged towards his sister and Dean started forwards just encase, but before he even got there it was over. Sammy kneed the guy in the nads, punched him in the face and then kicked him in the stomach, sending him crumpling to the ground with a scream.

"I told you never to touch me again, you prick. If you even so much as get within twenty feet of me again, I'll rip your balls off and shove them so far down your throat that you'll be couching them up for a month!"

"That's my girl," Dean laughed as he reached her.

Crouching down in front of the guy, Dean placed his hand over the guy's throat and squeezed. Leaning in he whispered in the guy's ear. "My girl knows how to kick ass, I taught her myself… now if you even so much as breathe an unkind word about her to anyone I'll come find you and make you bleed in new and interesting ways, am I clear?"

Nodding frantically, the guy scrambled away and ran past the bleachers.

"Dean I had that covered." Sammy huffed, her arms crossed in front of her chest, making her breasts press upwards against the tight top covering them.

Dean salivated over the perky nipples outline by the thin material, his dick twitching with interest at the sight.

"Sorry, baby, won't happen again." Dean said as he wrapped an arm around Sammy. He leaned in and kissed his sister where her neck and shoulder met as he led her away. Sammy shivered at the kiss and Dean gave her a cocky grin.

Sammy rolled her eyes. "Right."

Getting into the Impala, Dean turned it on, smiling as always at the low rumbling purr of the engine as he pulled out of the parking lot and drove them home. Sammy sat right beside him like she had for a couple of years now, all cuddled up against his side, the fingers of her left hand threaded through his right, resting on his thigh.

Sammy leaned her head on Dean's shoulder, her breath puffing against his ear, making him shudder as the warm air travelled over his skin like electricity. Grimacing, Dean adjusted his dick in the tight confines of his jeans with his right hand, remembering a second too late that Sammy's hand was gripped in his. Her fingers brushed against his dick, making it painfully hard at the touch.

"Really, Dean?"

"What can I say, you looked hot kicking that's guy's ass." Dean said with a shrug.

Laughing, Sammy pulled her hand from Dean's and cupped his dick, rubbing the length with a teasing touch. "Such a perv, getting off on me defending myself."

Dean groaned, his hips giving a shallow thrust upwards involuntarily at the feel of her tiny hand on his dick. She knew just where to touch him and how much pressure to give to keep him on the edge and waiting for more.

"Like he was going to do any actual damage, you may be a girl Sammy, but you're a Winchester first. There was no other result, but you giving the douche a grade-A smackdown." Dean answered with a winded laugh. "Besides, like I said, hot. Your tits were bouncing and you got a cute little flush on your cheeks, gets me hard just thinking about it."

"You and your obsession with my breasts," Sammy smiled as she started slipped the tips of her fingers down his pants, they glided across the tip of his dick with a feather light touch.

"Baby, it's another ten minute drive home, I don't think I can last that long." Dean breathed against her temple.

"So pull over," she smirked, giving his dick a squeeze before crawling over the front seats and into the back. "That little access road to the creek is just up ahead…"

The Impala came to a screeching halt a minute later as Dean parked it half way down the access road, out of the view of the highway behind them. Grabbing the lube from the glove box, Dean scrambled over the bench. Sammy had her back to the side of the car, licking her lips playfully as she took off her panties from under her skirt. The scrap of red silk and lace hit his face and he grinned, smelling her essence on the tiny piece of material.

Putting the lube in the back window for the moment, Dean pulled off his shirt and dropped it to the floorboard. Sammy sighed as she looked her fill, her legs spreading in invitation as she got more comfortable. Crawling in between her legs, Dean leaned in and nuzzled her neck, breathing in Sammy's scent. It was a perfect mixture of green apples and the smell of the Impala's leather seats… the two scents always made him think of home, of his Sammy and their Impala.

"Dean," Sammy moaned, arching her neck to the side to give him more room to kiss, lick and suck.

His baby was a sucker for wet kisses on her neck; she always got so hot and bothered when he'd spend hours sucking on her neck and shoulders. Sammy's hands wrapped around Dean's neck and pulled him close, her fingers threading through the hair at his nape, the simple act always comforted him as much as her.

Dean's hands slid up her body, touching every dip and curve that he knew would get her hot before cupping her tits, his thumbs rubbing teasingly around the rims of her nipples, making her gasp and clench her arms tighter around him.

"God, baby… love how much you react to my touch," Dean's lips travelled up and over her jaw and to her lips, taking them in a hungry kiss that set them both on fire.

"Please… gotta have you inside me, Dean… now!" Sammy cried, her legs wrapping around him as much as they could with the odd angle of their bodies.

"Kay," Dean grabbed the lube and hurriedly twisted off the cap, squirting some on his fingers before tossing it back in the window.

Sammy spread her legs even more and tipped her hips up under the skirt. "Okay, take your skirt off, Sammy."

"No, I want to keep it on, just encase someone comes along."

Dean nodded and then slipped his slick fingers under her skirt down to her hole. Sammy moaned at the first touch of his fingers around the tight ring of muscle as he rubbed the lube around the entrance before pressing two fingers halfway inside her in one smooth glide. She was still fairly wet from the quickie they had before he took her to school, so he made quick work of getting her ready for him.

Sammy gasped and mewled as Dean fingered her open, letting the tips of his fingers fondle her prostate with every thrust. Her nails pressed into the flesh of his back, making Dean all the more harder, so ready to pound into her tight little hole. Soon he had three fingers working in and out of her, the sound of them preparing her made a quiet harmony with Dean's groans and Sammy's needy gasps.

Pulling his fingers out, Dean settled back against the seat and pulled his dick out of his jeans and hurriedly slicked his dick up. Once that was done, he leaned over and wrapped his hand around her waist and manhandled her into position over his lap, her legs straddling him, knees pressed into the outer sides of his thighs. Sammy reached behind her quickly and grabbed his dick before the feel of her hole surrounded him. The feel of her tight wet hole wrapped around his dick always felt like coming home as he thrust inside to the hilt. Dean gripped her hips tightly and closed his eyes as the pleasure washed over him.

Sammy's arms wrapped around his neck and she gave him a wet sloppy kiss as she lifted up and slammed back down onto his dick, their breath mingling together as they groaned into each other's mouths. Soon Sammy was bouncing on his dick, crying out as it hit her prostate over and over, her tight heat clenching down on his dick with each spasm of pleasure.

"I love your cock, Dean… always so perfect inside me," Sammy gasped against his lips, her hands gripping the back of his head and she arched her back and rode him for all he was worth.

Letting his hands slip upwards under her shirt, Dean cupped her breasts, feeling the hard beads of her nipples rubbing against his palms as he massaged the fleshy mounds, groaning into her mouth as he came closer and closer to coming. When Dean felt his balls pulls up tight to his body, he gave a hard twist to her nipples and grinned as she screamed and clenched around his dick like a vise, coming.

Dean thrusts up into her tight body three more times before his vision whited out and he came inside her, spilling his spunk into her body with a satisfied grin on his face. Sammy slumped against his chest and pressed her face into his neck, her head tucked perfectly under his chin. He pulled her close, his arms wrapped tight around her as their bodies came down from the high.

"God, baby, that was awesome."

Sammy laughed and snuggled closer, tucking her arms around his back in between him and the seat. Slowly Dean's softening cock slid out of her and Dean's couldn't resist slipping a hand under her skirt and fingering her. He always loved feeling his cum slowly leaking out of her body, some throwback to the Neanderthal in his genes who wanted to make sure his mate was thoroughly marked and claimed, or so Sammy's told him.

Dean was never sexually territorial with any of the girls he was with before they got together, but Sammy was different. She was it for him, he'd known that since the moment she crawled into his lap when he was seventeen and said she wanted to be his girl.

"Come on, up. I'm starving and you promised this morning you'd make your meatloaf tonight for dinner, so time's a wasting." Dean slapped her ass and hauled her up off of his lap, ignoring the grumbles from her.

"Always thinking with your stomach, Dean." Sammy sighed with a pout before grabbing her panties from the floor and slipped them back on with a grimace on her face. "I swear one of these days I'm going to start making you wear a condom, I don't care how much you get off on your cum leaking out of me, it's gross."

"You've been saying that for two years, baby and you're still not making me," Dean laughed. "Just admit it, you like me spunk in your ass as much as I do."

Sammy blushed and ducked away from his eyes, refusing to answer. Dean grinned, his laugh getting louder. "Thought so."

Putting his shirt back on and wiping his cum and lube covered fingers on a wet wipe that Sammy always seemed to have on hand, Dean crawled over the front bench and into the driver's seat. Sammy crawled over a second later and tucked herself back into his side as he turned on the car. Threading his finger through her's and placing them on his thigh, he backed the Impala up and drove them home, a dopy smile on his face the entire time.

The end.

Author's Notes: This story is based on this prompt over at the spnkink_meme. What I ended up originally writing was something that took the long road to the actual prompt scene so I set that aside and wrote this instead. This story is basically set right in the middle of the original fic I wrote and is a part of what I am now calling the Good-Girls!Verse. Anyways, the longer fic that will be this fic's prequel/sequel is being written as we speak and will be posted during the spn_kinky_bang on LJ in January. Let me know what you think! ;p