People develop fetishes for all sorts of reasons, some convoluted, some extremely simple. Dean had developed a fetish for the sound of a shower running. If he heard the hissing patter of water against tile in a TV show, his cock was rock-hard within seconds. And the genesis of this fetish was beautifully simple.

Sam leaned up against him in bed, finishing the last of his salad wrap, licking the Caesar dressing from his fingertips.

Dean whispered, "So fucking hot, Sammy."

Sam arched his back at the feel of Dean's breath ghosting over the back of his neck. "Yeah?"

"Yeah. Things I wanna do to you…" Dean grabbed Sam's hand and drew his index finger into his mouth.

"Like what?"

Dean sucked the length of Sam's finger slowly until it was nice and clean. "Everything. But right now? Wanna lick you open, then fuck you."

Just about Dean's favorite thing to do in the entire world was eat Sam out like a girl. He wasn't submissive in bed, his Sammy, and he topped and played rough just as often as the other way around. But the feel of Dean's tongue in his ass made Sam lose his fucking mind. If Dean laid him out on his back, Sam would grab his knees and hold his legs open, shameless, all inhibitions vaporized, squirming, begging, demanding, making the most delicious cries and uttering the most filthy things Dean had ever heard come out of Sam's mouth (c'mon lick my hole Dean your tongue feels so fucking good do anything you want just don't stop c'mon fuck me with your tongue jam it in so fucking deep gonna make me come just like this yeah Christ suck it, like that, fuck, wish everyone could see how good you do that, want you to bend me over the counter in some gas station minimart, pull down my jeans, tell me to hold my ass cheeks open for you, and start licking my hole in front of everybody, make me scream, everybody watching you eat my ass like a pussy, spit dripping all over my balls, make me shoot all over your fingers and shove my come up inside me and then lick it back out…)

So yeah, pretty much Dean's favorite thing was licking Sam's ass. Once he did it for an hour straight, teasing with broad, flat strokes, making little kitten licks around the rim, then tongue-fucking him as deep as he could get, and pulling out to start the cycle again, not letting Sam come like he begged to. When he finally slid his cock inside Sam and fucked him stupid, Sam came so hard he passed out, and was so high from the endorphins he couldn't speak coherently for the rest of the night.

And yeah, that's what he wanted to do to Sam right then.

But Sam pulled away.

"Where you going, Sammy?"

Sam leaned down and kissed Dean. "You wanna eat me out and fuck me? Gotta go get clean for you."

Dean nearly came right then and there.

Sam took a small grey bag from his duffel and went into the bathroom.

Normally the words "anal douche" are not considered sexy. Until you learn how unsexy certain acts can be without cleaning yourself out first.

Dean heard the hiss of the shower turn on, and the patter of water against the tile suddenly becoming muffled. He knew that Sam was clipping the red plastic funnel over the shower head, lubing up his ass and working the nozzle up inside him, letting the warm water fill him up as much as he could take.

The thought triggered a spasm of pleasure so acute, his cock ached. Sam, bent forward in the shower, forearms against the tile, breathing deep and careful, taking the water in, taking it for Dean.

Dean stripped off all his clothes and lay on top of the bed, listening to how the water hit the tile again when Sam was ready to wash the outside of his body. Get himself clean all over for Dean. Knew Sam was letting the shower wash over him, was fingering his ass with soapy water, making himself all ready for Dean's tongue.

Sam came out of the bathroom, toweled dry and still damp, naked and gleaming, cock erect and curving up toward his stomach. And Sam's body would have made Michelangelo weep, so it was understandable if Dean felt a little moisture well up in his eyes at the sight.

Sam's mouth twitched at the sight of Dean's cock, so hard it looked painful. Dean pulled Sam down and kissed him.

"You do a good job? Get yourself nice and clean for me, Sammy?"

Sam nodded, brown eyes wide. He was shaking already.

Dean stacked the pillows on top of each other and positioned himself so his head was supported properly. "Lemme taste."

Sam crawled over him and settled into place, facing away from Dean, thighs spread wide, ass hovering over Dean's mouth.

Dean said, "Show me."

Sam shivered, then gripped his ass cheeks and pulled them apart.

"Such a little exhibitionist, Sammy."

"For you, Dean. Just for you."

Dean tipped his head up and breathed warm air over Sam's tiny pink pucker. Hard to believe that soon it would be stretched wide over Dean's thick cock.

Sam shuddered.

"There's just no fucking part of you that's not perfect, Sam. I just want to see everything."

Sam pulled himself open wider. "Fuck, Dean. Anything. Let you take photos. Videos. Anything you want. Just… god, Dean. Please. Do it."

Dean dug his teeth into the meaty part of Sam's thigh, eliciting a sharp intake of breath. "Do what, Sammy? Gotta ask nice."

Sam grabbed his nipples and squeezed them hard. "Lick my ass."

Dean smacked Sam's ass. "I said, ask nice."

"Please. Dean. Please, lick my ass. Need it so bad."

Dean pressed his tongue flat against Sam's ass and held it there, feeling it quiver.

"Please, c'mon Dean, please, lick me, so fucking good, please, PLEASE…" That was what Dean was waiting for, needed to hear. That shiver of desperation in Sam's voice. And he gave his little brother exactly what he needed. Like he always did.

He lapped at Sam's asshole languorously, slowly, taking his time, letting his tongue stay flat and soft, curling up at the end of each stroke. Sam moaned and rotated his hips, arching back into it, his cock dripping precum onto Dean's chest. When he hardened his tongue and stuck the tip of it inside Sam, Dean could taste a hint of soap, and knowing that Sam had worked a soapy finger inside himself to make himself ready for this was enough to take him right to the edge.

"Put your mouth on my cock, Sammy." And Sam wasted no time following orders. Dean sealed his lips over Sam's ass and sucked and licked at the same time, digging his fingers into Sam's thighs. Sam cried out, mouth wrapped around Dean's cock, and fisted his cock, shooting thick white jets of come over Dean's stomach. Dean pushed gently, indicating he wanted Sam to move off. "Use your hand." Sam slid alongside, and Dean fucked up into Sam's fist. "So beautiful when you come, Dean. Wanna see you." And Sam watched Dean contort, his whole body seizing as he came, spattering his chest and stomach, calling out his brother's name, as he always did.

Their breathing calmed and slowed. But Dean was far from done. Sam had recently been giving Dean shit about getting older, calling him a tired old man with no stamina. Dean was eager to prove him wrong.

Dean trailed a finger through the mess on his stomach, his clearer ejaculate overlaid on Sam's pearl-white come. Even Sam's come was beautiful, Dean thought.

"Get on your hands and knees, Sam."

Sam blinked at him.

"Do it. Head down, ass in the air."

Sam obliged.

At the feel of Dean's fingers pushing their still-warm come inside his ass, Sam groaned and spread his thighs open wider. "Fuck. Dean. Yeah. Yeah."

"Yeah, baby boy. Hope you weren't planning on getting any sleep tonight. Gonna take my time. Gonna fuck all this inside you with my fingers, and lick it out."

Sam's cock twitched, already starting to get hard again.

Dean scooped up another dollop of come and pushed it into Sam. "And you know what I'm gonna do then, Sammy? After I've licked you open, licked all our come out? I'm gonna fuck you till you scream my name, make you come in my fist, and I'm gonna come in your ass, fill you up, lick it all out of you again while you suck your come off my fingers, lick your ass until you get hard for me again. Gonna do it over and over until one of us can't do it anymore."

Sam sobbed into the pillow.

"How many times you think you got in you?"

Four. After the fourth time of Dean grinding into Sam's ass, making Sam come so hard his vision whited out and he nearly lost consciousness, coming inside him then sliding down, parting his shaking thighs, spreading him open with his thumbs, sucking his pink, swollen rim, licking out his come like a kitten lapping up cream, Sam collapsed, unable to move. The only coherent word he was able to mutter was, "Dean. Dean…"

Dean had only enough energy left to maneuver them both under the covers before he passed out.

In the morning, Sam wrapped himself around Dean like a tentacle creature and whispered, "That was. The best. Ever." Sam treated Dean like the second coming of Christ for two straight weeks, letting Dean pick the music without a word of complaint, bringing him pie, giving him back rubs, touching him constantly, and looking at him with so much adoration, Dean didn't even know what to do.

But it felt fucking awesome.

Eventually, Sam started giving Dean shit again for little things, but the look of worship never really left.

And that's how Dean got a shower fetish.