So I was browsing my dashboard on tumblr when I came across the lovely prompt mentioned in the summary and all I could think is 'wow, this would be great as a Rin/Rei smut fic!' I figured it would be perfect since my other fic Chasing Butterflies won't hit a smut point until later in the story (plus I'm writing a bit slow). Unlike that fic, this one will contain smut, although that won't be until the second chapter, if my audience thinks I should write one, that is :3 however this one has not been beta'd so please forgive me for any spelling mistakes and errors, I wrote it in a rush when the idea was fresh in my head and I barely read over it (oops :/) but I hope you all enjoy it :)

Title: Dirty Mind
Author: Me
Fandom: Free! - Iwatobi Swim Club
Rating: M for sexual situations, language and activities.
Pairing: Rin/Rei
Summary: Rin/Rei smut based off of this tumblr AU prompt: Person A is thinking sexually graphic or generally odd thoughts and suddenly panics and thinks "If you're a mind reader, cough right now." Person B coughs.
Disclaimer: These characters are not mine, and neither is the fandom they are from! All characters belong to their respective owners, I'm just using them to fulfill a plot bunny of mine.

"C'mon, speedo glasses, keep up or I'll leave you behind!" Rin yelled, still maintaining the same brutal pace he'd had all morning.

"I'm right...I'm right be-haaa-hind you!" Rei replied, only a little out of breath. He shifted gears, picking up speed until he was only a few feet behind Rin.

The redhead felt him approach, and quickly turned around to give him a quick smile before focusing more on the run. Rin missed it, but Rei's face was covered in a full blush, triggered only by the smallest—and sweetest—of smiles.

Now that everything had been resolved after the last relay, the two butterfly-swimmers had gotten pretty close, often going on long runs like this one a few times a week. Rei thought it would be a piece of cake since he was a track star before joining the swimming club, and because of all the working out he had to do to swim, but he soon realized he was wrong. Short sprints he could do—running ten miles without stopping? That was a bit much.

But it was definitely worth it, he decided, because this was valuable time that he got to spend with Rin. It still embarrassed him to think about it, but deep down, he knew he felt more than a friendship with him...wanted more than a friendship with him.

He had come to terms with it a few weeks ago, but just days after that, the dreams started.

The intense, vivid dreams that always left him aching for more.

They weren't an everyday occurrence, but they happened often enough for Rei to dread the sticky wetness in his bed the morning after while also anticipating the spent feeling that overcame him. The dreams were so powerful that even briefly thinking of them was enough to send pangs of want to his lower regions.

He shook his head, trying to reign his thoughts back in but failing horribly. He was still keeping up with Rin, but each passing minute he wanted to focus less on running and more on the guy in front him.

'He truly is beautiful...' Rei though wistfully, taking in Rin's form as much as he could. He was wearing his usual jogging suit, paired with the small ponytail in his ruby-red hair that served to turn Rei on even more. He swallowed, suddenly aware of the suffocating heat that seemed to be surrounding his body.

The blue-haired man further gave in to temptation when his eyes not-so-subtly found their way to Rin's toned ass, the object of his desire in his latest dreams. He's always known Rin to be rough around the edges, and because of that, Rin held the dominant position in his dreams, but lately, Rei was the one taking control. He couldn't imagine it happening that way if his dreams ever came to pass, but that didn't stop it from being a major turn-on for him. Just picturing Rin on his back, begging for more, already so close to the edge...

Rei was so caught up in his dirty thoughts that he didn't notice the rock in the middle of the trail, which he tripped over so violently that he fell to the ground.

Rin heard the loud 'thud' and turned around to see what happened. He could only smirk as Rei hastily stood up, rubbing the dirt from his track pants and fixing his glasses.

"Someone's too busy daydreaming I see," Rin said casually, jogging away.

Rei stopped in his tracks, the irony in the other's statement hitting him like a brick. It was so accurate that it was scary, if Rei was honest with himself. 'I guess that's what I get for thinking embarrassing things,' Rei thought to himself, a small blush dusting his cheeks.

When he saw that Rin was far ahead of him, he ran once more to catch up. After managing to get to Rin's side, he slowed up, letting out a breath he didn't know he was holding, and not just from the exercise. The fact that he fell wasn't enough to phase him, and he could only be thankful that Rin couldn't read his mind.

'Oh god, that would be horrible,' Rei though, mortified at the idea. He grew even more uncomfortable when he realized that there would be no way to know if Rin was in fact telepathic. 'I'm being irrational, it's scientifically impossible to read minds,' he berated. Even as he said that, however, the uneasiness he felt failed to subside. 'There's only one way to find out.' Rei reprimanded himself internally for even considering what he was about to do.

He took a deep breath, glanced sideways at Rin and thought, 'If you're a mind reader, cough now.'

Nothing could have prepared him when Rin coolly cleared his throat.

'Nope, no way, this goes against logic. It has to be just a coincidence.'

But Rei couldn't mistake the loud, obnoxious cough that Rin obviously directed towards him.

"R-RIN-SAN?!" Rei choked out, shocked beyond belief.

Rin let out a small chuckle. "Those are some bright ideas you have, Speedo Glasses. To be honest, I always took you as strictly vanilla, but I'm pleasantly surprised."

They both slowed to a stop. Rei's face was covered in the deepest, reddest blush known to man, mouth agape and eyes wide. No amount of words could convey the horror and embarrassment he felt at that moment, standing face to face with the one man he ever wanted that could apparently read minds.

"This...this defies every theory I've ever come across..." Rei whispered, barely able to process everything. "H-How—when did you—how is this even—" he stammered on, never uttering a complete sentence.

Rin took this moment to step closer to Rei, tangling the fingers on his right hand in short, blue hair as he pressed a chaste kiss against Rei's lips.

All of Rei's previous thoughts dissipated, along with the tension he felt before. His hands reached for the redhead's hips, his grip tightening as he felt Rin try to pry his mouth open with his tongue. With one sharp tug of his hair, Rei let out a small gasp, and Rin seized his opportunity.

Their tongues battled for dominance, equally almost, until Rin purposely ground against Rei's crotch, causing the other man to let out a small moan. Rin bit his lip, sucked on it gently and slowly let go. As they separated. they were both breathing heavily, the heat from their activities covering their bodies in a thin sheen of sweat.

Rei was the first to talk. "I have a lot of questions...since you know what I'm thinking, does all this mean that you return my feelings?" he asked tentatively.

Rin rolled his eyes at that one. "What do you think, Speedo Glasses? I wouldn't kiss you if I didn't."

A relieved smile covered Rei's face. He still had a lot to ask, but they wouldn't be able to cover any ground with their respective...problems. He came to a sudden conclusion as he pushed his glasses up and began jogging away.

"Oi, Rei, where are you going?" yelled Rin, a confused look on his face.

The blue-haired man just smirked, jogging backwards as he replied, "My apartment is this way."

He didn't have to tell Rin twice as the redhead swiftly passed him in the trek to the other's apartment, starting an all-out race to handle their 'unfinished business.'

Ahh, that's a great spot to end the story, don't you think? ;) I wouldn't mind continuing the story for another chapter or two if there's someone who really wants it, so just send in a review! Also any criticisms on my spelling or characterization are always welcome.