Mostly, he just thinks Dean looks really really good in the suit.
It's enough to make him distracted and snappy while they're moving through the warehouse. He lashes out at Dean about his stupid EMF meter. He feels bad about it a minute later, though. Really, it's not Dean's fault that he's driving Sam crazy. He doesn't even know he's doing it.
Sam tries to care about scanning the tangled ruins of the plane, but he's preoccupied with watching Dean out of the corner of his eye the whole time. He's thinking about how good that tie looks around his brother's neck, and how he likes the way Dean's brow furrows when Dean's thinking really hard.
He knows he should care about the stuff all over the emergency door handle, but all Sam can think about how Dean is brushing his fingers over his back. Wiping something on Sam's jacket – of course he is, the jerk – and the touch is light and brief, but it's enough to leave Sam with a semi and covered in goose bumps.
Because that touch starts him thinking about all the other ways he wants Dean to touch him and he's thinking about how he'd like to drag him back to the motel and bend him right over the table and leave him breathless. Sam starts wondering if Dean would let him use their ties to bind him to the bedpost.
Sam's about thinking a lot of things that have absolutely nothing to do with their case.
He hisses in discomfort while he's climbing over the fence, damning his stupid imagination and berating himself for letting himself get distracted like that. His only mercy is that Dean is too distracted with getting the hell out of Dodge that he doesn't really notice that Sam's barely managing to keep up with him, when normally, he'd be three paces ahead, using his longer legs to his advantage. He follows Dean to the Impala and tells himself firmly that there are more important matters at hand.
It turns out that Sam's dick doesn't really answer to his brain. Because when they check in with Jerry to tell him what they found out, Sam finds his concentration slipping again. He keeps looking at Dean, all rumpled now, shirt untucked, tie loosened. He barely holds it together throughout the meeting, and even so, by the time they're ready to leave, Sam is practically squirming in his seat.
He breathes a sigh of relief when Dean suggests they go back to the motel to grab some food and a few hours of rest and then research some more. Sam readily agrees and begins to form a plot in his head.
He puts his plan into motion the minute they enter the car. He shuffles through the shoe box of tapes and pulls out a Led Zeppelin tape – the one he'd caught Dean jacking off to in the back of the Impala a few weeks ago, and pops it in the player. Dean gives him this strange, surprised look at his choice, but doesn't look unhappy about it, and that is the first step.
The second step is as easy as popping open a few buttons and slipping off his jacket.
Sam smirks, knowingly, when he sees Dean glance towards the passenger seat with increasing frequency. He hitches in a quiet breath as when watches the line of Dean's throat bob as his brother swallows hard and grips the steering wheel tighter.
Step three calls for a certain amount of tact.
There is an art to staring. If you do it too often and too long, it starts to turn creepy. If you do it too little or too quickly, there's no guarantee that your efforts will be noticed. Sam has it down to a science. He inclines his head, just barely, acting like he's staring at the field passing by on Dean's side of the road. He lets his eyes slide just a little more to the left where he catches Dean's eye. He holds his stare for only a few seconds, but it's long enough to let Dean know it was deliberate.
For a long time after that, Dean stares fixedly at the road, a frown tugging at the corners of his mouth. And when he looks up again, Sam makes sure he's staring again. Catches Dean's gaze again and then turns away just as quickly, practically crowing when he sees Dean squirming in his peripherals.
By the time they pull into the motel parking lot fifteen minutes later, Dean is driving rather recklessly, and Sam has his hand on Dean's leg, fingers curled and digging into the soft flesh of Dean' inner thigh. He's breathing hard, not even trying to hide his arousal anymore, and Dean looks to be in about the same state. He confirms it when he kills the engine and doesn't even bother to pop the trunk to retrieve their things. Dean just marches around to the other side of the car and wrenches Sam's door open and Sam finds himself being hauled up and out by a firm grip on the front of his shirt.
He growls at Dean's pushiness, he's not in the mood for it today, and pulls himself out of Dean's grip just as soon as he gains his feet and his equilibrium. In one swift motion, he slams the Impala's door shut and backs Dean up against the side of the building, one hand pinning Dean against the painted clapboard while the other fumbles in Dean's pocket for the key to the room. When he kisses Dean, his brother tastes like fire. He tastes like guilty pleasures and Sam feels bad for enjoying it so much.
But Dean is kissing back, rough teeth and an inquisitive tongue. Sam finally finds the key and gropes for the door handle without looking, never breaking away from Dean. He sacrifices his grip on Dean's shirt so he can grope for Dean's shoulder, pressing tighter against his brother just as the key finally finds its mark and slides into the keyhole.
Sam comes up panting and Dean makes this kind of strangled whine at the back of his throat that goes straight to Sam's dick and there definitely needs to be a significant decrease in the amount of clothes they're both wearing right the fuck now. Reluctantly, he pulls away from Dean; but it's only long enough to drag his brother into the hotel room and slam the door shut behind him. Then he's all hands. He pulls the knot out of Dean's tie and slips it off his neck, draping it over his own shoulder. For later.
He's too impatient to take any more care than that. Buttons take too long; he opts, instead, to pull Dean's shirt up over his head and sets to working on Dean's pants. He tugs the fly open and shoves the material down over his hips hastily, exposing Dean's cock, already hard and moist at the tip as it points up towards his belly.
He takes a moment to just look at his brother appreciatively, toned skin and hard muscles, face flushed with arousal. He's saying something, Sam's not really sure, he can't hear too well past the blood pounding in his ears. But then Dean has his hands on him, is working at the buttons on Sam's shirt, and since Sam doesn't think he'd be able to manage such a feat himself, he lets Dean do it, busying himself with setting his mouth to Dean's jaw.
His teeth scrape against stubbled skin and he leaves soft bites all the way Dean's neck, pausing when he reaches his brother's collarbone. He sucks on the hollow of Dean's throat, tonguing the patch hard until he's sure it'll leave behind a bruise. Dean groans and manages to pull the last button free and Sam helps him pull it off when his brother slides the material down over his shoulders.
He makes quick work of the rest of his clothes. His pants are a size too big, so when he pulls his belt free, they slide effortlessly down off his hips and land in a pool on the floor around his ankles. Sam's not wearing underwear.
It takes him a minute to realize he can still feel a brush of fabric against his chest, a barely noticeable weight wrapped around his throat. He reaches up to pull the tie off, wondering why Dean left it and is startled when his brother growls. Next thing he knows, Dean has a hold on Sam's wrist and he's pulling it away, hissing, "leave it," before he's smashing his lips up against Sam's, hungry and forceful.
Sam leaves the tie, but Dean's tone is another matter entirely. He stoops and retrieve Dean's tie, has to fish around in the pile of discarded clothes for a few seconds before his fingers close around it and then he's up again, pushing Dean backwards towards the bed.
When they reach it, Sam shoves Dean down and crawls onto the bed on top of him. He grabs Dean's wrists and pins them to his sides, shifting so his knees are settled on top of them, leaving Dean trapped while Sam's hands are still free. Dean could probably get away if he really wanted to, but one look at his heaving chest and flushed face tells Sam that his brother is enjoying perhaps more than he's willing to admit.
Sam smirks as he raises the ties, lets it slip through his hands, fine and silky, and loops a knot into it. Dean's eyes widen and he opens his mouth to say something and that's when Sam shoves the material into Dean's mouth and quickly ties it tight enough that only several minutes of hard work will free his knots. Dean grunts, but his tongue is stopped by the knot in his mouth and he glares up at Sam instead.
It's all bravado and show, Sam knows. He can feel the way Dean's hips twitch beneath him, can hear his breath hitch, the tiny moan that isn't completely muffled by the gag. Sam takes it all in and bites his lip hard enough to draw blood, focusing on the pain to keep himself from coming right there.
"Fuck," he mutters, stroking reverent hands down the hard planes of Dean's chest, before grabbing Dean's wrists once again. He drags them – with minimal resistance from Dean – up over Dean's head and curls his brother's fingers around one of the wooden slats of the headboard. He bends down to ghost his lips across the shell of Deans ear, relishing the tremor it provokes and when he speaks, his voice comes out as a husky snarl, dark and heavy with lust. "If you keep you hands there, I won't tie you. Move them and you'll regret it."
Dean grunts again, but after a few seconds he nods and tightens his grip and bucks his hips pointedly.
Sam finds the lube. In the back pocket of Dean's jeans, of all places. And he has a hell of a time rummaging around the room for it. But it's worth the time it takes because he watches Dean the whole time and his brother doesn't move. He just lies there, eyes tracking Sam's progress, nostrils flaring and chest heaving with every breath he takes. He's still gripping the headboard with white-knuckled fingers.
It's maddening. By the time he finds the tiny tube tucked into Dean's pocket his fingers are shaking and he sighs in relief and hurries back to the bed. He crawls up the length of his brother's body like a predatory cat until he's pressing kisses into Dean's neck, tasting salt and sweat and a metallic sort of tang that is entirely Dean. He fumbles with the cap and when it pops off, the lube spills all over his fingers, far more than he needs and it drips down onto Dean's belly.
Sam ignores it, tosses the tube aside and will worry about it later because this is taking way too long, dammit and he needs to be inside Dean ten minutes ago. He slides his hand between the cheeks of Dean's ass and slides it into his entrance with no preamble. Dean groans and bites into the gag, arching his back and flexing his hips, trying to push further down onto Sam's finger.
Shit, and he's tight. Sam breathes hard and curls his finger, feeling the way Dean's muscles alternately clench and relax around the intrusion. He thinks about how that tightness will feel around his cock and he groans, quickly adding a second finger.
Dean's making all sorts of interesting noises now, all of them muffled behind the gag, but Sam's almost certain at least one of them is a fumbled attempt at Sam or maybe damn. They kinda sound alike. Sam dips his head and leans forward to plant sloppy kisses along Dean's jaw. He scissors his fingers for a moment longer, loves the way Dean writhes beneath him and is feeling rather squirmy himself, so he adds a third and works Dean open as fast as he can.
And finally finally, he moves into position and is sliding into Dean in one slick motion and the pressure around his cock is enough to leave him breathless, desperate to move, afraid that if he does right now, he'll lose it. He sucks in a lungful of air and lets it out slowly and then leans forward, planting one hand on Dean's hip and the other to the side of Dean's head and begins to rock, pulling almost entirely out of Dean before pushing right back in, hard and fast and reckless.
He's still wearing his tie, he realizes in some obscure part of his brain and he watches it dizzily as it trails across Dean's torso, back and forth, back and forth as he thrusts into his brother. Dean is wriggling and shifting his hips to meet Sam's thrusts and out of nowhere, there's a sudden tight pressure around Sam's neck. He looks down to see one of Dean's hands wrapped tight around the tie, pulling it tight against Sam's throat.
Every breath is a hard battle fought, and he doesn't even think to berate Dean for disobeying because he's seeing stars behind his eyes and just when he thinks he might suffocate, Dean relents, lets him heave in a few unhindered lungfuls and then the pressure is back. Sam never stops moving, even when he can't breathe, he still moves and all he can think is shitshitshit and Dean and fuck because that's all there's room for right now.
He shifts his grip on Dean's hip and wraps his fingers around Dean's cock, jerking him off with quick, short strokes.
Sam's not really sure who comes first, the edges are kind of fuzzy, details blurred. But he does know that it starts just as his lungs are beginning to ache again and there's this strange tightness coiling in his spine. As soon as Dean lets up on the pressure on his neck again, just as he gasps hard, Sam feels Dean's cock jump in his hand and his muscles clench around Sam's dick and that's all it takes before he's arching his back and biting his lip to keep himself from yelling.
He milks Dean's orgasm right along with his, thrusting a few more times into his brother while he slows his strokes over Dean's cock until he's dry and softening in his hands. He slides free and Dean tugs on his tie until he pitches forward and flops on the bed beside his brother, raising shaky fingers to tug at the knot of the gag.
As expected, it takes several moments, and by the time the knot slips loose, Dean's muttering impatiently, words Sam can't decipher but he figures they probably don't bear repeating. When the gag finally falls free, Sam flicks his eye up to catch Dean's gaze. His brother just stares back for a moment, panting hard. Sam expects to be bitched at, or reprimanded, or something. Instead, Dean just tugs on his tie, pulls him in for a kiss.
When they break apart, Dean smirks.
"What?" Sam asks, suspiciously. He knows that smirk.
"'Bout time you got laid. You were getting cranky," his brother laughs. God, he's a jerk.
Sam rolls his eyes and shoves the gag back in Dean's mouth.