It happened the same way it always did.

They were speeding down a highway, middle of the night, heart of the desert, so the sky was a reeling black bowl filled with so many stars it looked like you could scrape off a whole handful without making any difference. They didn't have anywhere they had to be in a hurry, coming off a hunt that'd gone great, nothing new on the docket yet. Dean had cut the music hours ago in case Sam wanted to sleep, and it didn't look like he did, but it was also one of those rare times when the quiet felt just fine to Dean. Nothing but the two of them, the music a pair of bodies made in a small space, the singing of rubber on asphalt, and the horses under his baby's hood.

Sam was looking out at the stars, at the rolling hills covered in rabbit brush and scrubby snow, and his hair curled so nice around the shell of one ear where Dean had tucked it for him earlier. He knew he couldn't actually, but he pretended he could see the calm, sleepy beat of his pulse under the point of his jaw, in the darkness. Sam's lashes flicked and his eyes shone in the ghost-light coming off the sky, and Dean wanted to reach out and touch him. Catch fingerprints and calluses on that night's stubble.

He stayed put, both hands on the wheel.

Sam moved, soft shff of denim on the worn leather, crossed those long legs of his down in the footwell. Dean looked, followed them all the way up from the ankles to where they met. His jeans were pulled tight across his groin, had the shape there on full, careless display. One hand rested dangerously close to it, all slim fingers and big knuckles.

Sam swallowed, entire long column of his throat rolling, and he stretched a little with it, too. So his shirt came up and showed off a sliver of skin Dean knew would be cabin-hot against his mouth, a mole just above his waistband, a wisp of dark, grainy hair growing along the line of his center. Dean was watching, all of him. Tracing the way the intense flare of his shoulders narrowed so suddenly into his hips. Taking in how casually he was slung in the seat. Mapping the gentle rise and fall of his pecs.

"Eyes on the road." Sam's voice was soft, husky from hours of silence, and there was a smile in it, too.

Dean rolled his eyes, made himself focus even though the highway was perfectly flat and straight and there hadn't been another car since sundown. Bitch.

"Jerk." Like he could read his damn mind sometimes, he swore.

Dean made it about a minute and a half. Until he caught movement out of the corner of one eye, movement that translated into a tongue dragging slow across lips, slicking them up, before the bottom one was pulled almost casually in between a set of teeth, and bitten hard.

Sam's breath got just a little faster. Dean pulled over.

No motels for miles, not even any buildings. Neither of them could get on their knees in the snow outside. Doing anything on the hood was out of the question, and not just because scratches were practically a guarantee; bottom would freeze right to the paint. Dean ran down all of that in the very back of his mind as he and Sam gasped and ground and pulled at each other in the front seat, mouths swollen and hands pressed firm to each other's rising cocks.

"Back seat," Dean said roughly when they broke for a second so they could breathe, gasping and swallowing. The windows were already steaming up.

Doubt flickered in Sam's face. "Sure?"

"Did it all the time when you were in high school." Dean grinned, and it'd been long enough that it almost didn't even hurt when he teased, "Whatsamatter, Sammy, afraid Dad's gonna catch us?"

Sam snorted. "Jerk."

"Bitch." Dean wiped his lips with the back of his hand. His whole mouth tasted like his brother.

They just sat up there in the front for a couple seconds, breath and heartbeats deep and fast, until Dean added, "You wanna try the hood, be my guest, but if you leave any skin on my car - "

Sam was already yanking the door open and swinging his legs out, the sudden blast of cold like a slap to Dean's still-damp lips.

He scrambled out himself, wishing he had a beanie, even though he hated them, because the air might as well have been a pair of clamps on his ears, and swung around to the trunk to get lube out of his duffel. Nobody'd be tapping anybody else's back door out here, they didn't have the time or supplies to prep properly (and had learned the hard way that not prepping was about as much an option for this as it was for a hunt), but it was still a good thing to have anyway. One hand full of the bottle, the other cupped over his crotch to try and keep the shrinkage to a minimum, Dean got up to the back seat and found Sam...struggling.

His shoulders were laid awkwardly against one door, neck twisted in a way that would've had a chiropractor screaming in order to keep his skull off the handle, and his middle was kind of crunched up. He had his legs bent like he was gearing up for a frog hop, one knee pointed at the ceiling and the other almost touching the back of the driver's seat. His boots were planted on the other door, which had Dean briefly entertaining fantasies of breaking both his ankles if he'd gotten mud on it, and his face was screwed up in discomfort and confusion. The only remotely sexy thing about the whole position was how tight it drew his jeans across his cock.

Dean yanked the door open and had to sidestep fast when Sam's legs suddenly shot out like snakes in a can. Sam looked up at him with wide eyes.

"What the hell're you doing?" Dean asked.

"Uh, trying to fit?" Sam crawled backwards, pushing himself slowly upright with his elbows, and stopped with a hiss when there was a loud pop. Dean grimaced himself, own spine twinging sympathetically.

"And you gotta do it in the most awkward way possible? You're gonna pop every joint you got outta place and I'm not spending all night putting 'em back in for you."

"How d'you want me to do it, then?" Sam snapped back.

The mood was rapidly dying, along with Dean's erection. He tossed the lube to the floor with all the loose coins and empty ammo boxes and leaned in through the open door. "C'mere."

After five minutes of "Wait, cut it out" and "What're you even trying to do here?" and "Ow, ow, ow, ow - jeez, Dean, I don't bend that way!" Dean pulled back out.

"You sure do when you're stretching before a run. Gumby guy. Take a video next time to prove it." Dean rolled his years-old bad shoulder in its socket, one hand on it. It wasn't feeling so hot all of a sudden, after wrestling with Sam like he was a damn toddler again and fighting a one-kid war against pants. "How d'you usually get back here?"

Sam treated him to a particularly scowl-y bitchface. "I don't."

"What d'you mean, you don't? Course you do. All the time."

"When's the last time we had sex in the back seat, Dean?"

"Uh…" He could've sworn it'd been just recently, but the more he thought about it, the harder a time he had remembering. There'd been plenty of beds. Couches. Back alleys behind bars. Church pews. An autopsy table, once, but that ended awkward because it turned out Sam didn't have the kink he thought he did, or maybe he did and the smell of dead people's insides had just ruined it for him. But, yeah. No Baby. Not for a long, long time. "You were...seventeen?"

"And how tall was I then?"

Dean nodded to himself. His face was starting to hurt. "But you sleep back here all the time. You slept back here just last week. How d'you do that?"

Sam had that caveman-brow-pout thing going on. He rolled over onto his side, and started coiling himself up. It was a long process. Dean squinted, and thought about a video he'd seen once of an octopus cramming itself into a baby food jar.

"Holy crap, dude," he said once Sam was, for all intents and purposes, fetal. "No wonder your back hurts all the time."

"It doesn't," Sam muttered.

"You sure ask for a lot of back rubs." Dean rolled his eyes at the look Sam shot him. "It was a joke, Maslow. Don't need another love-language lecture." He rubbed his hands briskly together to try and warm them up. "Look, just - get back in your little pose and let's at least give it a shot. I'm freezing my ass off out here."

"Fine." Sulky, Sam pulled his legs up, and Dean climbed in.

It didn't sound right, but he guessed that he must not've been at his full size when Sam was seventeen, either. He remembered there being a hell of a lot more seat back here. His head hit the window almost as soon as he was in. He had to wedge one knee in between Sam's ass and the back of the seat, ignoring the way he jumped when he accidentally pinched him, and then the cap was resting right on a seatbelt. The other knee was perched precariously right on the very edge of the worn leather. He had one hand on the back of the back seat, the other on the back of the front. Closing the door meant twisting almost a hundred and eighty degrees at the waist, which something low in his back did not like, and dragging his head and shoulders along the roof. When he was done, Sam's legs were wrapped around his waist and not in a fun way, boots turned sideways on the window. Dean couldn't even bring himself to bitch at him about the inevitable smudges.

Closed up in the car, deeper in each other's spaces than the last time they'd been tied together, they just stared for a second that kept on getting longer. Dean's back was tight against the roof, knees already complaining. Every breath he took came straight out of Sam's mouth, hot and moist, and he was rapidly getting tired of the taste of him.

"Happy?" Sam asked.

"Perfect fit," Dean replied.

Either of them could've called it off. Dean could've admitted that it wasn't gonna work, Sam could've been adamant about the damage even five minutes like this was gonna do to both of them. They could've mutually agreed the moment was gone and just gotten on their merry way. They were both stubborn sons of bitches, though. The same bitches. And that was a big part of the problem.

Might as well get this show on the road.

Dean kissed Sam. Dropping down to do it meant his ass was on Sam's giant, muddy boots and his shoulders were screaming at him for being at an angle they were definitely not meant to be. Their teeth clicked together, Dean accidentally spit into Sam's mouth in a way that couldn't have been less hot if he tried, and only a few seconds in, Sam groaned with something that clearly wasn't enjoyment.

"Okay, now my back hurts," he said when Dean pulled back.

"Stop whining." Dean shifted his weight to his knees so that he could fumble with his belt and jeans. A sickening pinch pressed slowly through one, and he gritted his teeth and pushed past the pain as he pulled himself out, and then Sam.

Neither of them were even a little bit hard anymore. Dean didn't give a shit.

One hand on Sam, the other on himself, Dean ignored Sam's bitching about how cold his fingers were and started stroking the two of them slowly out, building the same rhythm. It didn't feel great at first. He definitely was cold, and Sam was not making this easy, with all his squirming and huffing and bitchy little brother whines. But, again, stubborn son of a bitch. Dean kept at it.

And, finally, it started paying off. Sam's huffs and whines started slowly turning into ones of pleasure as he stiffened again, lengthened out, filled Dean's hand, and his hips started rolling with Dean's movements, much as he could manage with how he was now. Sam's pleasure kick-started Dean's own, had him growing heavy across his palm as electric waves sparked to life in his dick and balls. When Dean looked at Sam, he caught the wet shine of bright eyes and an open mouth.

"Attaboy," Dean said huskily. "Here we go."

They could salvage this. Maybe the orgasms wouldn't be great. They'd probably be feeling being crammed back here for the next week or two. But they could still get off, still bask in that glow, and it'd fix all the snapping and squashing and cramping…

Dean's bare hands, rough with calluses and scars, would start chafing on the silky, dusky skin of their shafts before too much longer. He twisted again, groaning at the pain in his back as he snagged the lube off the floor, then uncapped the bottle and started a messy pour straight onto Sam's cock, smirking at him. He'd drench him, see if he couldn't get his own dick in there, jerk the two of them off together. He didn't remember that the lube had been out in the very unheated trunk as they drove through a twenty-degree night, or realize how cold the bottle was in his hand, until it was way too late.

A few things happened at almost exactly the same time. One, the near-frozen lube hit the head of Sam's cock. Two, Sam thrashed violently, yelping like somebody'd just cut his hand off. And three, four, five, and six, Dean's leg slipped off the edge of the seat, his shoulder hit the back of the front seat and popped cleanly out of socket, Sam's knee nailed him right in the balls, and gravity wedged him into the footwell more tightly than a bullet in a barrel. He managed to knock himself in the head pretty good on the way down, and get one leg stuck straight up with his already-complaining knee cocked at a dangerous angle.

"I fucking told you," Sam yelled, one hand on his junk and the other his own knee, pulled way out of line when it hit Dean.

Dean was too busy trying not to puke to tell him the hell he had.

It didn't take Sam long to figure out Dean was actually hurt. He dropped his own drama, pried him off the floor, popped his shoulder back in with a gristly crunch, and walked him slowly around to help him catch his breath. They both limped through the snow. Sam's hands were warm and steady on Dean's back and stomach, apologies soft and sincere, and Dean appreciated it and all, but he was mostly focused on the size his ballsack would probably be swollen to by tomorrow.

He knew that Sam'd fucked his leg up, too. He knew he couldn't really blame him for a reflex. And he knew that none of this would've happened if he hadn't insisted on doing it in the back. But he'd already had a "owning up to his faults" kinda mood a few weeks back, so it was gonna be a good six months or so before another one rolled around.

Twenty minutes later, they were sat in the front seat again, keys in the ignition and heat on full blast. They were in their respective spots, not touching, not talking, not even really looking at each other. It was only because Dean could see Sam without even moving his head that he knew he'd been frowning to himself for a while before he broke the silence.

"Dude, I'm pretty sure that your car doesn't want us to fuck."

"What?!" Dean whirled to face Sam, which the nauseous ache still sitting low in his belly was really not a fan of. "How can you even say that? What the hell is wrong with you?"

Sam's shoulders hitched up in the beginning of a shrug. "Well - "

"Just think about all the times we had sex in here," Dean continued. "Front and back seat. Handjobs. Blowjobs. Dry humping. Full penetration, which I'm counting even though neither of us had any idea what we were doing and it was super gross and hurt really bad. Sam." Dean went to point dramatically into the back, but it was with his bad shoulder and he had to clutch at it and settle for a much weaker point than he'd wanted, along with a gasp of pain. "You lost your virginity back there."

"...are you sure you're remembering right?" Sam squinted. "'Cause I could've sworn - "

"By any standards that any normal person would consider," Dean declared, talking over him, "your first time was in here." He glared. "Sleep humping doesn't count, Mr. Fourteen-Year-Old Pervert."

"Not even when you both wake up halfway through and decide to just go for it?"

"This car..." Dean ran a hand lovingly over the steering wheel, "...is probably the only reason we're where we're at now. She's always been our space. She's why we could start fucking in the first place."

Sam was squinting again.

"Stop imagining having a threesome with the car," Dean commanded.

"I'm not!"

"Yeah, you are."

"Well, now I am."

"See? I knew it."

"If either one of us has imagined fucking this car," Sam proclaimed loudly as he pointed down between them, "then it is definitely you."

"You got a problem," Dean stated, and Sam snorted. "I'm serious. Have some goddamn respect, Sammy. She's practically our matchmaker. Our - marriage bed, even. This…" He swept a hand, this time on his good side, grandly out to indicate the entire dash. "...is what an ally looks like."

Sam just stared at him for a long second, like Dean had knocked every word in the dictionary out of his brain. Then he scoffed in disbelief, shook his head, and looked away, and Dean had a flashback to him being twelve so strong it was practically time travel.

"Okay, smartass." Dean hooked a thumb over his pounding shoulder. "Get in the back."

Sam whipped around to stare at him in disbelief. "You can't seriously - "

"No, not that, Sam. C'mon. I meant you're riding back there…" Dean stared Sam down, arm, stomach, knee, groin, and literally everything else hurting, "...'til you can give my baby the respect she deserves."

There was lots of eye-rolling and grumbling and general bitchiness, but Sam did eventually unfold himself from the passenger seat into the dry, freezing night air. Soon as the door closed behind him, Dean threw the car into drive and revved the engine.

He didn't even move an inch before Sam's hands slammed down on the hood and he flung a downright murderous look in through the windshield. Dean put it back in park, cranked his window down, and leaned out.

"You dented her, forget the back," he said seriously. "You can ride in the trunk."

"Are you freaking kidding me right now?" Sam demanded.

"You know I wasn't actually gonna drive off without you."

"Oh, weren't you?"

Dean rolled his eyes. "Look, you were being a giant dick, and it's my job to correct that. It's in the big brother handbook."

"Right next to the blowjob instructions, huh?"

"Still being a giant dick. Been one this whole time."

"I didn't practically give you scoliosis wedging you into the back seat and then throw a fit when it turned out there's no physical way in hell two guys over six feet tall can have sex in a space smaller than a coffin."

"Throw a fit?" Dean exclaimed. "I am wounded, Sam! I oughta be in a sling right now! And I'm lucky I didn't pop a ball on that doorknob you call a kneecap."

A silence stretched out, just the quiet sound of the engine wasting gas. Dean's breath steamed in the air, heat billowing out around him through the open window, and Sam was still leaning so hard on the front of the car he was starting to seriously worry about him wearing out the shocks. Finally, Dean rolled his eyes.

"Just get back in the damn car. Be lucky if we hit a motel before sunrise."

"Should've kneed you harder," Sam muttered, and then straightened up. Or tried to, at least. His hands weren't coming off the Impala's frigid black mirror of paint. Dean watched, lower lip pulled back into his mouth. Sam stared down at the bare skin, tugged again and, when absolutely nothing budged, looked up at Dean in dawning horror.

"I fucking told you so," Dean proclaimed, throwing his arms wide and not even caring when one shoulder yet again fell free.