Dean thinks Sam needs to practice fighting off a demon. Sam agrees, so he reluctantly allows Dean to possess him. Once he's actually in his body, though, Dean quickly becomes distracted.

"I just don't get why." Sam picked at his turkey sandwich. "Wouldn't you be able to sense any that even got close to us? I mean, you'd definitely be able to sense it if I got possessed."

"Yeah, but I'm talking about a just-in-case thing. If I'm ever not around."

"Why wouldn't you be?"

Dean didn't answer. Something twisted hot and hard inside Sam's left calf, so he cleared his throat and changed the subject. It didn't help the pain all that much.

"In that case, there're charms I could wear. I know how to make at least three. There're tattoos I could get…"

"You can lose charms, or somebody could steal 'em," Dean pointed out. "Tattoos can be burned off. We can do that stuff, definitely can't hurt, but the best thing you could possibly do's learn how to recognize when somebody's trying to possess you, and fight it off. Last line of defense." He picked up his complimentary coffee, sniffed it. "You've never been possessed before, not even by a ghost. You got no experience, but we've got everything we need to give you some right here."

"Ghost possession's really rare. Demonic's even rarer."

"Not anymore." Sam swallowed. "Look, Sam. I'd just feel a whole lot better about…hunting, and the Trials, if I knew that you knew how to throw a demon."

That got Sam's attention.

"So…when and where d'you wanna do this, then?"

"Well, not a whole lot else we can do right now." Dean gestured out the window, where a storm that their waitress had referred to as a gullywasher was socked in. "So we can do it today. Back in the room."

"You serious?"

"Dead, Sammy." Dean motioned for the check, then grinned at Sam. "Can't wait to get home and get inside you."

Sam rolled his eyes.

Back at the motel, the very first thing Dean did was fix Sam's ponytail for him. His hair had frizzed out hard in the humidity, just like it always did, rapidly passing "annoying" and heading for "totally unmanageable." He missed the mountains.

He liked the feel of Dean's fingers on his scalp, though. In his hair. Just like always. He wondered what it'd feel like when Dean was actually inside him in the truest sense of the word, no barrier whatsoever between their souls.

"Okay." Dean patted Sam's shoulder once the mess on his head was as secure as it was going to get. "Go ahead and lay down. This might be…uh, not a whole lotta fun, and I don't want you hurting yourself if you thrash around or something."

"Is it really gonna be that bad?" Sam asked with a frown. "…you've been riding your own body for years, haven't you? How much experience do you actually have with this? Possessing people."

"Enough."

"How long's it been since you were in somebody else?"

"'S fine."

"I'm just not sure this is gonna be a useful – "

"Sam. Look." Dean cut him off. "I got this, okay? Trust me. Now lay down, on the bed, so that we can get it over with."

Sam didn't ask anything else, kicking his boots off and going for the bed. He steadied himself without thinking about it. Seven and a half years of muscle memory.

"What the hell're you doing?"

Sam flushed, corrected himself. His healed, whole left leg functioned without any issue. "Nothing."

He laid down. Dean settled in next to him, and Sam didn't say anything when he took his hand. It helped some, where Sam's calf was cramping passively.

"Gonna be fine," Dean assured. "Won't take that long." A pause. "Course, we might end up doing it again and again. And again. If you can't get the hang of punching me down inside your body."

"That's awesome," Sam deadpanned. "Can't wait."

Dean chuckled, and then he must have unhitched himself from his body, because black smoke began churning fast into the air above them.

Sam pushed himself up just in time to see the last of it leave Dean's mouth, and then Dean's head fell to the side, eyes and face blank. He knew that if he felt for a pulse, there wouldn't be one. His stomach lurched and his calf tightened. The last time he'd seen Dean like this, it'd been back at the cabin, Gordon's corpse cooling out in the main room and Dean's soul in Hell.

Right now, though, it was here. The cloud had collected just below the ceiling, and Sam looked up at it. It was tough to connect it to Dean. Sam knew, logically, that was his essence, the real him, but some part of him didn't believe it.

He laid back down, staring up at it (him) as it boiled and shifted above him, a microcosm of the stormclouds outside. It was a deep, rich black, but the longer Sam looked, the more convinced he got that there was a green tint to it, deep inside and around the edges. Like the clouds that formed tornados. There was some sort of lightning flickering at its heart, too, and the entire thing held a velvety depth. It was like looking at one of those illusion books for kids, but a really good one, the kind that nearly made you feel like the two halves of your brain were sliding away from each other because it didn't make sense. Sam almost thought that if he reached through it, it wouldn't be the ceiling of the motel room he touched.

So this was what a Knight of Hell looked like. Damn near the toughest thing in existence, the being with the most staying power, period, only excepting the top two archangels.

Sam jolted out of it some, realizing that he'd lost almost a minute just looking at Dean. Time to get this show on the road.

"Come on. Hurry up." Sam smirked a little, false bravado. Could Dean feel how nervous he was, outside of a body? That was something to ask him once he could talk again. "Or are you waiting for me to get the lube out?"

Dean took that as permission, apparently. He rushed Sam, who had a split second of full-blown panic when he was dead certain he didn't actually want to do this, but then Dean was in him, entering him through his nose, mouth, eyes. It smacked his head back into the flat motel pillow, his body arching off the mattress as every muscle flew taut. Sam let go of Dean's hand as he dug his fingers into the bedding, fisting tight, sweaty handfuls.

It didn't hurt, not by any means. But it sure as hell wasn't comfortable, either.

The texture of it was about what he'd imagine swallowing leather might feel like if somebody blended it up into a shake. He could feel the crackle of the ozone that came before a lightning strike or a ghost attack on his tongue, and of course it all smelled and tasted overwhelmingly like sulfur. Sam would've gagged if he could but it also, for some reason he couldn't even imagine, got a little half-twitch out of his cock. He collapsed weakly onto the bed as it ended.

Dean's smoke didn't fill Sam's lungs or stomach once he was in. He flooded every inch and crevice of him like a liquid, shadows falling along his joints and bones like they were meant to be there. Dean knew what he was doing, where he was going. Sam could feel him, snug in his head and heart alongside himself, and it was strange. It felt like a violation, his body wanted to reject Dean. But at the same time, it also felt oddly right. Safe. Good.

Dean was soft and living armor under Sam's skin. It felt like his voice, his movements, the flicker of his eyes and fingers, his jokes and the gentle way he brushed Sam's hair out of his face and the drape of his arms when he held him. All of it, condensed down into something that coiled around Sam's organs and seeped into the cracks in his brain. A distillate in his blood and breath, whispers and grinning kisses inside his cells.

Sam's eyes had fallen closed when Dean was in the process of coming in. He could feel tears gathering under his lids now and wasn't quite sure why.

Apparently, Dean wasn't, either. Why're you crying? Sam jumped a little. It was Dean's voice, but…rougher. Older, somehow. There was a sharpness to it, a razor blade with two dozen different sides, and it also sort of sounded like several of him were talking at once. This must be what he sounded like inside his own head, which kind of...blew past weird, all the into "alien" and "unnerving."

I don't think you want a weirdness contest. I got plenty of ammo in here already. Like how goddamn bright it is in here, dude – seriously, I've seen a lotta souls, I don't think that's normal.

Sam cringed.

Are you crying 'cause of your leg?

His leg…yeah, it was cramping pretty hard, but it was kind of a distant thing for him at the moment. Most of what he could feel was Dean.

Aw, Sammy. You're gonna make me blush.Even harder than I was when you were ogling my smoke. Sam could feel Dean's focus, and it was on his left calf. Why the hell's it still so messed up? I fixed it. Why's it hurt? Why're the muscles doing that?

"W – "

Sam didn't even get out a full syllable before Dean shut his voice down. Or took control of his throat, probably. Sam jerked, wondering how in the fuck he was supposed to answer.

You can still talk, dumbass. Just think at me, okay? But pretty much no demon out there's gonna leave you access to your voice. And we're practicing here. Speaking of practice, lemme tell you what I'm gonna do: leave you in charge of breathing. Among other stuff. Could automate it, like I've got on my meat suit, but it's a hell of a lot harder for you to fight back if you've gotta focus on managing your bodily functions.

Sam was, all of a sudden, incredibly and horrifyingly aware of breathing. And swallowing his saliva. And keeping his eyes closed (that was a conscious choice? It'd never occurred to him). But he managed, You're talking about bodies like they're cars.

That's all they are. Machines. And it's better to think of 'em that way. You're not fighting me for control of you, you're fighting for control of the meat-robot you ride around in.

Dean sat him up all of a sudden, and Sam opened his eyes, blinking away the remaining tears that were blurring his vision. It was massively disorienting, his body moving without him wanting it to. It actually made him kind of nauseous. But then Dean dismissed the feeling, and the nausea vanished.

Dean turned to look at himself. Wow. Am I one sexy son of a bitch or what? He reached out to stroke his gelled-up hair, run Sam's fingers down his body's face, and Sam rolled his eyes.

Dude. Seriously?

Yeah, seriously. I never get to do this. When I look in the mirror, all I see's my real face. A pause. For real, what is up with your leg?

He reached down to rub at the calf through Sam's jeans. Super weird it's cramping like that, you'd think I never fixed it at all. Then he made everything release.

It was kind of like he'd snapped his fingers inside Sam, except there was no snap and no fingers. The pain and tightness were just instantly gone, and Sam definitely wasn't going to bitch about that.

Good. 'Cause I got enough to bitch about for both of us. Like, how d'you stand all this hair? You got any idea how obnoxious it is? And d'you even know how much tension you're carrying in your shoulders? He swung Sam's legs over the side of the bed. Ooh, shit, these're long. You're just big, aren't you? Dean looked around, focusing on a couple different things, then grimaced with Sam's face. Forgot how much human vision sucks. And yours is even pretty good. Gimme a sec, okay?

There was a flicking noise, a sudden flash of darkness, and then Sam's vision was exponentially brighter, crisper. It was like putting on glasses after spending his entire life without knowing he needed them. He could see individual raindrops falling outside their room's window, the wood grain on a building across the street, silent lightning dancing in red and blue flashes high up in the dark clouds. His eyes, he realized, had just gone black.

Dean got Sam up, walked him around like a puppet or a toy. The gait felt weird, different from how Sam usually walked. More swagger to the shoulders, feet spaced oddly, like he was compensating for slightly-bowed legs.

Dean made it maybe three feet from the bed before exclaiming, I knew it was big, Sammy, but damn…how the hell d'you walk around with this monster cock hanging down your leg all the time?

Sam blushed, actually saw the heat around the edges of his new eyes. Dean grinned inside of him, he could swear he felt it. Not that I can't handle it, of course.

Sam got halfway through rolling his eyes before Dean took that away from him. He switched his eyes back, too, and Sam actually missed the demon vision, even if it'd made obvious how filthy their room was.

The black eyes being gone made something else obvious, though. It wasn't just Dean Sam could feel inside him, it was power, too, obscene amounts of it, more and more reaching his notice by the second. Napalm and uranium laid dormant in his muscles, a thousand volts thrummed quietly through each vein. He didn't have access to any of it. But if he had, it felt like he could disperse the storm above with a wave of his hand, crush the motel straight to the ground, run all the way to Argentina without so much as breaking a sweat.

You could, Dean agreed, but then you'd drop deader than a doornail the second I left your body. If a demon pushes you past your limits, you'll die, and then their energy'll be the only thing keeping all your organs running. They can hold your soul hostage that way, keep it from going up. Or down. But in your case, it's definitely gonna be up.

This energy, Sam was pretty sure could keep him alive for a million years. It was a blue star in his chest, requiring constant tiny adjustments to keep it from going supernova. He could feel the way that Dean was self-correcting almost every second, and it blew him away.

So what'd happen if you just…stopped holding back?

Sam's mind was suddenly full of a picture that hadn't come from him. Most of western North America replaced by a gaping crater pouring smoke into the atmosphere, the ocean from Hawaii to Japan black with debris, and what remained of the continent scarred and glowing. His heart lurched into his mouth, but then it was gone.

Probably not anything near that big, Dean admitted. But I don't really know, and I'm sure as hell not gonna find out.

Sam couldn't deny it was more than a little scary, that Dean had to be thinking about it constantly to keep something like that from happening. He'd thought he was in better control of his powers. Hadn't anybody taught him more effective methods? Were there even any?

Dean's irritation scraped over him like a Brillo pad. I can keep a lid on it just fine. You really think I'm gonna go Chernobyl in the next five minutes?

No. Sorry. Sam was going to have to try and keep his thoughts under control.

Yeah, I'll say.

He was still mad. Sam could feel that like an offshoot of his own emotions, wondered if that was what it was like for Dean all the time, but as soon as he thought that, Dean's feelings were closed off to him. He winced inside himself, apologized, but Dean didn't acknowledge it.

Y'know, you're not really fighting back at all, Dean pointed out eventually as they wandered around the room. Can't really give you any pointers 'til I know what I'm working with here.

Right. Sorry.

Sam really didn't have any idea what he was supposed to do. Just move his body on his own? As they passed the bathroom, Sam tried to turn and go in, but didn't manage to make so much as a single nerve fire.

Is that it? Dean asked incredulously. Seriously? Sam, that was pathetic. Is that really all you can offer? Jeez, I guess you're kind of a wimp once you're cut off from these, huh? He flexed Sam's biceps appreciatively.

Stung, Sam tried harder, threw more of himself into it. He turned his head, so jerkily he was sure he pulled a muscle doing it, and then Dean put him back down, smoke against his soul like an empty velvet glove.

You're gonna have to try a whole lot harder than that. C'mon, Sammy, I've seen so much better from you…where's all that fire now?

He grabbed Sam's backpack, putting it on the table and taking out his laptop. As he fired it up, Sam demanded, What're you doing?

Gonna look at porn. What else? Dean sat down. I love the internet. Back when I died, you had to go to a newsstand and buy a skin mag, and if you were looking for anything other than girls or vanilla, you were screwed.

As Dean typed in the password he shouldn't have known, Sam took a second to try something out, sort of folding in on himself to try and shield his thoughts. He doubted it was going to work, but it must have, because Dean praised, Attaboy, good start as he swiped over the trackpad.

Sam's backpack was still within reach. There was a flask of holy water in the side pocket, a canister of salt in the gaping front one. The water was closer but he'd have to unscrew the lid if he went for it, so salt it was.

He threw himself against Dean's smoke, and it felt like he punched through it to seize his own arm. He lunged for the salt, but his fingertips barely brushed the canister before Dean snapped his wrist to the table, pinning Sam in place with his will.

I'm actually impressed, that was - Dean stopped abruptly. Sam knew he was feeling something off him, tried to hide it, but he was still in charge of his breathing and was having to pant, so he wasn't quick enough. It wasn't just in his soul, anyway, it was his body, and he didn't know how to cover that up. Are you actually getting off on this? He paused, as Sam flushed so hard and deep he was sure his soul turned pink. Wait. You've got a bondage kink, don't you?

Uh, no, I definitely don't! Sam tugged at his wrist. It wasn't budging, and a second later, Dean herded him out of his arm anyway.

Oh, you definitely do. I'm inside you, remember? I can feel everything you feel. 'Specially this.

Gleeful, Dean rolled Sam's hips, straining swollen cock against fabric, and Sam seethed. A second later, though, Dean sobered. Sam felt him even out inside him. The barrier between their emotions was gone now, apparently.

It's actually real common in hunters, Dean explained. Having a thing for being tied up, I mean. Held down. Especially if you were raised in the life. Think about it. You're into psychology, right? You grow up learning how to tie and break knots, practicing how to get outta cuffs, rope, zipties. You're just obsessing over being captured and tied up, you get taught to fixate on that, being caught by things you're hunting. Your dad tells you it's the worst thing ever to not be in control of the situation. Being at somebody else's mercy is the ultimate taboo.

Sam swallowed, and not just because his mouth was full of spit. He'd gotten harder during Dean's little Freud lecture, even though he hadn't meant to, shape of his dick fully visible now in his loose jeans. Dean had noticed that, too. Sam could feel his delight.

New plan, Dean announced.

Dean straightened up, putting Sam's arms behind his back. He crossed his wrists, holding them firmly there like they were tied in place, and hooked his ankles around the legs of the chair. It honestly felt like he was bound. Sam felt his heart rate rise.

What're you doing?

If you don't like it, stop me. I know you've got the juice to do it.

Sam felt Dean's hold over his body relax. He could take control back right now if he wanted to, piece of cake. But he didn't move, just floating free inside his own flesh.

Thought so. Dean was smug.

Sam's belt, button, and fly undid themselves, Dean's telekinesis like gathering sparks in his smoke. Sam protested (Now what're you doing? Stop!), but still made no move against Dean. Goosebumps were coming up on his skin, nipples hard, his breathing fast and his cock more than half-erect.

Dean pulled him out, and it was odd, wrong, thrilling, being held in place and touched by something inside his own body that wasn't him. Sam was swallowing hard, over and over again, muscles straining and trembling.

Dean could feel it all, Sam was fully aware. How good it was. How bad he needed it. He also knew Dean wasn't going to stop, and that just made Sam harder.

Seriously, dude, you're fucking huge, Dean commented, almost casually. You got any idea how much fun I'm gonna have playing with this thing? Almost wish that it was mine…although I guess it does kinda belong to me, doesn't it?

Sam swallowed again, and a bead of precome gathered pearly in his slit.

Would you look at that…I knew you got wet, but it's pretty early for that, don't you think? You're not even all the way up yet.

Dean's psychic touch on Sam felt almost like a hand, but not quite. It shifted, fluid, and there were too many fingers, so maybe it was a few hands coming from multiple directions, stroking him expertly out to his full length.

Cut it out. Sam gasped even inside his own head. Th-this wasn't part of the deal.

You can stop me any time you want. Maybe they were tentacles, the way they wound around Sam's girth, not hands. Fight me off, Sammy. I'm a demon, I'm possessing you, I'm doing something with your body you don't… Dean's smirk blazed against Sam's soul. …want me to. Don't you want me gone?

He flexed Sam's biceps and lifted his wrists a little, like an invitation for Sam to break his hold and get loose. Sam didn't take it, and Dean smirked again, this time with Sam's mouth. Then he kept stroking.

The touch all of a sudden changed. Sam jumped, gasping, which was how he realized just how much control Dean had ceded to him. It was like a mouth now, warm and wet and soft, but the hand-things were still there, too, moving in gentle circles around his shaft and crown. There was even a light stroking on his balls. He could see the dusky skin on his cock moving, just barely, under invisible pressure, and that should've been gross. Sam kind of wanted it to be gross. But it was hot instead.

Sam's thighs shuddered as he dripped precome onto his jeans. He moaned out loud, stomach tight.

Dean's smoke, twined with Sam's soul, pulsed. He felt him do something a lot like biting his lower lip, and a wordless groan of pleasure echoed through Sam's body.

You're really sensitive. There was a jittery quality to Dean's voice now, reminded Sam of how hard it was to think clearly when he was horny. Thought you'd've practically built up a callus, 'cause you had to be jerking it every day. Right? Cooped up that tiny cabin?

Sam prickled some, would've commented on that, but Dean dipped into his slit. Sam saw it widening and then precome being tongued out. It hung thick and translucent in the air before falling like the rain outside.

Sam's vision sharpened again, Dean's eyes going black.

For a long time, Dean just teased him. He got slowly rougher and rougher, working Sam almost up to climax before going instantly back to feather-light touches and bringing him away from the edge. Sam was blushing, sweating, panting, his head tipped back, his eyes aimed unseeing at the ceiling. A frustrated moan rolled out of him every time his orgasm was denied.

The amount of pre drooling out of him was insane. He'd never had anything like it before. His pubic hair was sticky and matted, his thighs wet. Dean was practically milking him and Sam couldn't do anything about it. He was a prisoner inside his own body, held firmly in place by his wrists and ankles.

And you like that, don't you? Dean purred to him.

His smoke was starting to prickle and fizz inside Sam. He wasn't sure what that meant, but when he closed his eyes, he could see black-green pulsing right behind his lids.

The touches suddenly got firmer, more frantic. The hands were all over, Sam's base, his balls, his shaft, his cockhead. The thing that mimicked a mouth was there, too, slicking rapidly up and down him, precome rolling around it like a miniature tidal wave. It clenched tight.

There was an unexpected blast of pleasure back up between Sam's hips, flooding his stomach with heat. Tears prickled behind his eyes. His face tingled as he mewled, arching his back. It was only because Dean was still holding him "tied" in place that Sam didn't fall right out of the chair.

Sam's thoughts were scattered, paper swirling in a storm drain, Dean taking him apart by working his prostate like a worry stone cradled in one big, rough hand. That image somehow made it even better.

Sam's orgasm was like thunder, huge and deafening. Lightning-ignited fireworks went off in his stomach and groin, every part of him stimulated. He bucked wildly, but Dean held him in place, under control, at his mercy. That only made him come harder.

The sheer intensity hit him like a sledgehammer between the eyes. He could've drowned in it and would've loved every second. There was so much it was like coming twice. Two climaxes in one, massive, fitted together like puzzle pieces, twined around each other like Dean's smoke was inside him. The both of them finishing together, same time, same body. Sam was howling inside his head, couldn't even talk.

Talk about mutual orgasm.

That sounded like Dean. But locked into this kind of pleasure, the two of them were so blurred together it could've been Sam, too. Or both of them, at once. The same as how they were coming.

Sam collapsed back into the chair when the tsunami let go of him, a wave washing up, spent, on a distant shore. He felt all fuzzy and loose, vision spotty, limbs hanging like dead weights. He was suddenly yanked up when smoke streamed out of his mouth, choking him for a few seconds, but then he slumped down again like a puppet with its strings sliced. He stayed there, panting, for god-knew-how-long until Dean came up behind him, back in his own body.

Dean helped Sam up from the chair, onto shaky, near-useless legs. There was come on the table, Sam noticed distantly. Dripping off the edge, the underside. Sam's arm over his shoulders, Dean got Sam's boots off before he took him into the bathroom, then sat him down on the toilet. Sam blinked up at him as he pulled off his jeans and then his boxer-briefs, tossing them into the tub. Dean went to wipe him down with wet toilet paper, and Sam gasped at the touch of the cold water, every nerve in his body still sparking and sensitive. It felt good to get cleaned up, though. Everything from his navel to his knees felt sticky.

Sam half-fell, half-leaned forward, so his chin was on Dean's shoulder and his arms were draped around him. He wanted the contact and Dean felt so warm, smelled so nice.

"That was so good," Sam gushed, a giant, stupid smile plastered across his face. "That was the best I've ever had. It was so good."

Dean straightened him up and smiled at him. "Yeah, I know it was. Who'd've thought you were such a kinky son of a bitch?" He grabbed a threadbare towel and started drying Sam off. "I mean, not like you spent the better part of a decade holed up in the ass-end of Nowhere, Colorado, experimenting on monsters."

Sam laughed easily.

"'S the first time I've ever done that," he whispered to Dean. "Been tied up. Sort of. During sex." A cloudy memory surfaced, djinn-induced hallucination. "For real. I've never done any kind of…bondage. Control…play. Whatever it's called. I don't think I knew for sure I liked it, I didn't even…know there was a word for it."

"I'm sure glad you enjoyed yourself." Dean patted Sam's shoulder, and then he straightened up, and Sam wished he could still feel Dean's feelings because now he looked sober, almost guilty. "But I definitely screwed up back there, and…I know it."

"What d'you mean?" Sam asked him, surprised.

Dean rubbed the back of his neck, looked away, and his eyes were black for a slice of a second.

"You were right. What you said earlier, 'bout how it wasn't part of the deal…we should've talked about it beforehand. I just. Didn't know I was gonna do it 'til the time came, y'know? But I should've stuck to keeping it just a training session, since that's what we both agreed to." He grimaced. "And I shouldn't've ignored your nos. No means no, even if…I could tell you were enjoying it. I don't want you to think I'm some kind of – I've never pushed past somebody's no before. Not unless they had a safeword. That's another thing I should've done, given you one of those." He eyed Sam for a second, then began, "See, it's a word that you can – "

"I know what a safeword is," Sam interrupted. "Dean." He reached for his hand, damp and cool. "It's fine, okay? I'm fine. I liked it, and we can do it better next time. Plan it out, use actual rope…or cuffs. But we probably wanna tape up the cuffs first. Me bleeding on the bed might be a little bit of a mood-killer."

Dean relaxed bit by bit as Sam spoke, he could see that even through the haze of the afterglow. He smiled at him, a flash of teeth.

"So you wanna do it externally next time, huh? I can get that." Half-playfully, he added, "Guessing you don't want me inside you again. Ever, probably."

"I didn't say that." Sam pulled Dean down, into a kiss, and the sulfur in his mouth tasted like home.