I just headcanon their team to be their biggest shippers okay.

This was supposed to be explicit (uncensored version on AO3 if anyone's interested!), so I hope I removed everything that doesn't comply with FF's rules. Let me now if something is too... Detailed.

For context (which is, clearly, the basis of most of my headcanons): Gou, Seijuurou and Haruka are all at Hidaka's University. Gou is the manager, Seijuurou the captain, Haruka doesn't care about anything but swimming as usual. When Rin has holidays, he comes and visit them. The rest is history.

I have no idea how this got so long.

"Hi Seijuurou-kun, did you need –"

Gou never got the opportunity to finish her sentence, as she heard the office door being swiftly locked behind her back.

She slowly closed her eyes while exasperation washed over her. She turned around, distinctively hearing cackles and rapid footsteps fading away.

"You've got to be kidding me…" She mumbled. "How old are they again?"

Seijuurou didn't answer her, his face desperately hidden in his palms. She giggled, seeing he'd been just as fooled as her.

"So… You have your own Nagisa, uh?" she asked, half irritated, half amused, one eyebrow slightly arched. This prompted him to glance up at her with piercing eyes, the corner of his lips curling into a dangerous smirk.

"Well, well, well. You see, I'm glad you're mentioning Hazuki. Your boy has corrupted my team beyond repair. He came once to visit Nanase last year; and scattered absolute chaos in his trail. I thought it would be a one-time thing because they were under his demonic spell, but they actually started doing this on their own after. Welcome to the mess he left behind."

Gou let out a throaty laugh. She should have known better.

"Worse", he kept going, savoring is indictment, "they text each other about it – from what I've gathered – to try new combinations and plot against innocent souls like mine." Gou rolled her eyes as he was affecting a dramatic impression, incomprehensibly proud to play the part of the victim.

"They really don't respect you, do they?"

He flinched at her taunt and nervously scratched the back of his skull.

"I guess they estimate the kicks are worth the punishment. I don't think it's ever worked, and they always cry when I make them race afterwards, yet… They keep trying."

She sighed. She thought she had to be more mature to be able to handle grown-up men now that she was in university. Oddly enough, it seemed that the men in question were even more infantile than in high school.

"Anyway," he started again with a triumphant expression, "it's okay. I found a parade. We can escape through the window in the storage room. We'll wait a little outside and sneak back in in a bit. They'll eventually open up."

Seijuurou frowned for a second, as he witnessed her face clouding, unable to figure out why.

"So… You've been locked in before? … With… whom?" she tried to ask innocently. Unfortunately for her, her own face was her worst enemy and betraying her full blast.

A mischievously grin crept up his face. He crossed his arms, slightly straightening up.

"Jealous, Matsuoka?"

"Don't even try to captain me." She snapped back.

She wasn't sure if his thunderous laugh resonated within her bones or if the walls actually shook a little, but her heart skipped a beat as she felt a warm rush of lust flowing through her veins. Unaware of the effect he had on her, he met her gaze again, with an even wider, jubilant, obnoxious smile. He was still waiting for an answer. She averted her glance, not caring to hide her annoyance.

"Maybe" she muttered. He swallowed his sigh. So cute. She was so cute. So cute it hurt. He offered her a goofy grin and dragged her in a kind embrace. He knew she never stayed mad when she rested on his chest.

"Don't worry. If I know a way out, that's because I actually needed one. As a matter of fact, I already had someone in mind at the time." He added with a wink and pink cheeks. "But I guess you already know that."

"Yeah, well, about that way out…" she led the conversation away as she could already feel the flush rising on her face at the evocation of him liking her such a long time ago. She'd been really stupid. Also, she could hear his drumming heart and that clearly didn't help her own. He chuckled a little and reluctantly broke the hug.

"Come on, I'll give you a leg up."

.

Sadly, when they went into the storage room, they were greeted by a sealed window. Seijuurou groaned, but before they could turn back to the office, the door slammed on them, the ominous click of the key hurriedly following, leaving them gaping in pitch dark. For a split second, Gou swore she could hear Nagisa's infernal chortle, as if his presence haunted the place. She recalled Seijuurou telling they all texted to conspire. She had mentioned the year before that she was considering applying to Hidaka's university. She shook her head. There was no way this shaitan could have foreseen that far ahead… Was it? Maybe she would have a quick word with him.

They stood motionless for a moment, taking in their new setting. The captain eventually cleared his throat.

"So… It appears they figured it out. I'm sorry. It's even worse." He seemed sincerely disappointed his plan didn't work out.

Gou attempted to find him by locating his voice and bumped into him. He tried to grab her but missed as she bounced back.

She didn't know if it was for the darkness around her, but his mere contact, as fleeting as it was, sent shivers down her spine. Maybe the fact that he was only wearing his customary briefs and his opened jacket played a part. There was a lot of accessible skin. They were locked in, alone, in the dark… She tried to push her filthy thoughts aside, but it was pointless. They were in this situation because apparently the whole swimming team wanted her to entertain such considerations. If only they knew that she didn't wait for their little help…

They both randomly gesticulated to find each other. Their arms clashed and they backed up a little, scared to inadvertently hit the other. Knowing her boyfriend's extremely loud nature, Gou realized he'd been silent for a suspicious amount of time.

"Are you sure this wasn't your plan all along?" She teased.

He relaxed, relieved she wasn't mad at his poor escape attempt.

"I wish I was that smart." He chuckled lightly. His confidence boosted back, he slowly started to reach out for her again in the obscurity. He finally brushed her shoulder. Not knowing which part of her body it was just yet, he let his hand wander a little bit, softly skimming at her arm and then up her neck.

She leaned in his touch and blindly stepped ahead to find him as well. Guided by his limb making its way up to cup her cheek, she easily located his chest. She took infinite pleasure to slowly raise her fingers up to his face, but not without relishing in every shape she encountered on the way, making out his upper abs, pecs, collarbone, and trapezius, before reaching her destination. He tremored under her touch. "Although…" he hesitantly murmured, his voice edgy, "Now that we're here… I mean… We can always arrange something…"

"Oh. So you were thinking the same as me then." she exhaled, hardly holding her thrill. He didn't bother to reply, rushing to capture her mouth, his strong arms locking around her waist, pulling her closer

Gou let her hands roam everywhere on him. They were pressing into their respective warmth more passionately, and their touches became hungrier and more impatient. He felt her lips curl up against his, but before being able to wonder what that was about, he froze as her digits were heading down.

"GOU!" he hissed as quietly as he could manage. She sneered back.

She broke the embrace and turned around. "Let's find somewhere to —"

"Wait, where are you?" she smirked when she heard the distress in his voice, evidently caused by her sudden disappearance.

Afterwards, everything happened too fast. She felt the tip of his fingers tentatively grazing against her shoulders. Then there was a loud noise, a grunt, and he collided against her back. She didn't fall all the way down, rather stumbled and crashed against a pile of boxes.

He was completely bended over her, in a very suggestive pose, and damn her whole body went alight. Ignoring the fact that he literally tripped and fell on her, without missing a beat, huge possessive palms clasped her ribcage, while he drunkenly inhaled in her hair.

"Sorry, I didn't get you had this in mind…"

She giggled but she had a hard time catching her breath to reply. "Well, we have to try new things, don't we?"

He buried his head in her neck, kissing and nibling, enjoying the heat of her body squeezed under his own.

.

He collapsed on top of her, sprinkling her shoulders and neck with kisses, before soughing "I love you" in her ear. His breath got stuck in his throat and he petrified. Shit. Shit shit shit shit shit. Although it'd been true for a while now, he had never told her before. Was it too soon? Was it… Maybe not the best romantic moment to do so? What if he scared her off?

She snickered under him, as she felt in real time how he instantly regretted is actions. She started to wriggle, and successfully disentangled herself from his grip. Gou spun, grabbed his cheeks and smooshed him fervently.

"I love you too, dummy."

He finally let out the breath he was holding and wrapped his arms around her, planting pecks everywhere on her skull and face, prompting more giggling from her.

"You know…" he started again, blissful from the confession, "I want you again so bad right now… But after the ruckus we've made, if by any chance it went unnoticed, maybe we should keep a low profile. Just for now."

"Yeah" she groaned "I hate it when you're right, but I guess they won't be much longer."

He could hear her grin when she spoke again. "Turns out time flies abnormally fast when you're around."

" 'Around'?" He grazed her ear with his teeth, and she hissed.

"Shut up."

He lets out a triumphant giggle.

They proceeded to straighten up, smooth and put back in place their clothes, and blindly reach for the wall. They sat against it, comfortably resting against each other, and for the few minutes that followed, he couldn't stop caressing her hair and planting kisses in her neck, unweariedly repeating how much he loved her, until both of them dozed off.

.

They did not know how long they were out, but someone finally opened up again, only to discover their tangled frames, both fully clothed. Well, "fully clothed" was kind of an overstatement regarding Mikoshiba, but according to his own standards, one could consider he was fully dressed indeed. They were still sitting on the floor, leaning back against the wall, almost innocently napping, his arm around her shoulders, and her head resting on his chest. The sudden spark of light basking their faces woke them up, and they groggily blinked, trying to remember where they were and why. Kisumi's suspicious voice interrupted their peace of mind.

"Hum. You two look a bit too dressed in my opinion… But it does smell like sex in here."

Seijuurou sighed and braced himself for the punishment he obviously had to hammer his team with, but he froze, listening to an ominously familiar roar. The two lovebirds recognized Rin's voice from afar before he actually entered their vision field.

"MATSUOKA'S HERE?" Seijuurou murmured in panic, his eyes almost falling out from his skull.

"Yeah! You didn't know?"

"No, I did not."

"Isn't he supposed to sleep at your place?"

"I thought it was next week!" All blood abandoned his face as he saw his life flash before his eyes. As much as he enjoyed their most recent activity, he would have never taken that risk knowing he could have possibly been caught by Rin, retroactively being terrified of what his fate could have been in this worst-case scenario. Besides, he wasn't completely safe yet. And here he came…

"ARE YOU GUYS COMPLETELY OUT OF YOUR GOD DAMN MIND? WHY would you lock them in like this?"

Rin slammed the door more open, squinting eyes locking the room down. His murderous glare settled on his sister's head, only a few inches away from his former captain's naked chest and saw red. Thank God she was yawning and wiping sleepy tears from her bleary eyes, or he would have seen her hand casually resting over his knee, too.

He strode into the room, snatching his sister away from her lover, unabashedly throwing daggers at him. Gou was finally coming back to her senses and started to laugh at her brother.

"Onii-chan, stop looking at him like he's so dangerous, you make it seem like he's a predator. Just stop already."

Instead of following her advice, he immediately loomed all over her, inspecting her, trying to find any sign of a line being crossed.

"Gou, are you okay? How long have you been in here? Did he do anything to you? Should I punch him? I really wouldn't mind you know." Then he turned his head with the obviously guilty man blinking at them. "Don't you dare touch my sister, Mikoshiba."

"Onii-chan," Gou giggled again, "can't you see everything's fine? Leave the poor man alone. He's been tricked into this as well."

"Alright then," Rin slowly turned around, looking for a culprit "who should I beat into the ground then?" Kisumi smartly took a few steps back. Seijuurou couldn't help a chuckle at Matsuoka's ridiculous behavior, which earned him another polar glare. "You're not in the clear yet, Mikoshiba." Alright, that was enough of this. He quickly stood up, his captain stance taking over.

"You know, Matsuoka, I am fairly disappointed by your lack of faith and wild assumptions over me. Do you really think I would harm your sister in any way? Maybe we should settle this in the pool, once and for all."

Rin's eyes went treacherously ablaze. "You're ON."

Gou swiftly averted her gaze away, biting her lips. It always made a huge impression on her when her boyfriend went into captain mode. What has he done to me? She desperately thought. WHY am I thinking about having sex with him ALL the goddamn time?

She let them get out first, but not without smirking at how they tried to push against each other's shoulder to be the first to go through the door.

Although not by much, Rin won the race. He victoriously tried to taunt Mikoshiba, but said man was resting his forehead against the ledge of the pool, already wallowing in his own failure. He should have expected to be a little less in shape after giving a specific someone all his energy less than an hour earlier. My bad, he thought.

With a despicable grin plastered all over his face, Rin started to strut around his dwelling former captain.

"So. Now that this is settled. Mikoshiba. Stay. The. HELL. Away. From my sister."

The memory of her pleading him to end her misery whirled back at Seijuurou, and he couldn't help but snap back "What if she wants to come closer?" before regretting being born, ever. The gloomy silence that followed was even worse than the yells he was expecting.

"What was that?" Rin asked with a white voice.

The captain's whole face cringed in anticipation. Yet, the next exasperated voice that ringed in his ears was Gou's.

"Sei…" She started as she facepalmed, "If you knock on the devil's door, you can't really expect him not to answer back."

Her older brother froze mid stance. Did he really hear that right? "… 'Sei'?" he repeated menacingly.

Gou gasped and tried to shrug it off, but she was already wearing an incriminating crimson shade. Rin slowly spun to gauge his future victim.

"Mikoshiba… Is there something I should know about?" he growled. Startled by the unexpected turn in the conversation, Seijuurou flushed as well, quickly opening and closing his mouth, at loss for words.

The older Matsuoka uncharacteristically relaxed while he calmly strode towards the pool. "Good thing you're already in the water. It'll be easier to drown you."

His survival instincts kicking in, the team captain hopped out and ran around the pool, Rin following closely on his heels.

Several hysterical "No running around the pool!" started to fuse from everywhere. Never mind how hard Mikoshiba would discipline them later, the whole team was cheering and howling with laughter, having the time of their lives. The plan had outstandingly exceeded their initial expectations. Definitely worth it.

"MATSUOKA RIN!" the culprit froze upon hearing his full name. Gou felt her chest swell with satisfaction. This worked every time. "Would you mind stopping acting like a petulant child? Since we're down to this, I'll have you know that Seijuurou-kun and I have been dating for the past few weeks now, and I am in no way interested about your opinion about it. Do I make myself clear?"

Unluckily for her, it was way, way too much for him to handle in such a short span of time. Rin took advantage of Seijuurou being completely dumbstruck by her statement, ogling her with disgusting puppy eyes dribbling with how infatuated he was with her; and he tackled him straight into the pool.

Mikoshiba, in a turn of event, being taller than his aggressor, managed to escape his grip and resurface, pushing the mad man's head underwater every time he tried to get out and snarl something at him.

"MIKOSHIblrlrlb – WILL YOblrellbrl – GOING TOblrlllblr – MURDERblrlblblbr – OKAY STOP"

"Sorry? I didn't hear you."

"I will exterminate you later." Rin eventually spat, catching his breath. Had he been able to kill with his sheer willpower, Seijuurou would already be a dead man.

Gou seized her chance.

"Okay, now that this is settled, I would appreciate if you crashed at somebody else's place than Sei's tonight."

Rin gawked at her for a few seconds, but Mikoshiba anticipated him trying to jump at his throat, and he pushed him underwater again. The older Matsuoka was now fighting back with so much belligerence that he managed to escape the taller man's clutch, and immediately went for his legs to unbalance him, attempting to drown him once more. Both redheads disappeared under the surface, and for a moment, the only thing the audience could make out was a lot of messy struggles and an incredible number of angry bubbles popping out. As much as the whole team was enjoying the drama, some of the swimmers eventually intervened when it became obvious none of them was going to make out of this alive. It took four of them to separate the fighting men.

No one said anything for a whole minute, the two fools trying to steady their panting. Finally, Rin barked "There is no way I leave the two of you alone now."

"Onii-chan", Gou started while stamping her foot, "If you persist being a maniac, I will personally lock you out. Or you want to watch? Is that what this is about?"

Her older brother choked and went ablaze from the suggestion. He tried to retort something, anything to shut her up, to convince her that what she was doing was utterly wrong, yet no good reason made its way up to his tongue. He stared at her. She was standing with her feet slightly apart, hands pinned on her hips, hovering over the pool, glaring with a lot of assertiveness. This specific stance wasn't without reminding him a very particular person that was mere inches away from him, whom he swore he'd find a way to annihilate.

He eventually gritted his teeth and capitulated in front of her determination to have sex with her legitimate boyfriend. He sent a raging hit in the water to unwind his frustration. But she wasn't completely done with him.

"God you really should get laid and get out of my sex life." As she said so, she peeked at Haruka, pouting in one of the corners of the room, annoyingly waiting for the performance to be over so he could resume to his laps. Maybe she would innocently prompt the team to lock them in, if anyone survived this cursed rollercoaster day. Rin reddened and growled but said nothing. Seijuurou took this as his cue to put distance between him and the angry Matsuoka, and he swiftly got out, stretching a little bit.

Unexpectedly, it was Kisumi who eventually broke the heavy silence.

"So… It was actually pointless to lock you guys in? You were already dating?"

Their captain observed Matsuoka struggling to dominate his violent cravings, and with an unprecedented wave of wisdom, he chose the safe option of getting further away. Gou was staring at Shigino, not really knowing which answer would be less aggravating considering the already poor emotional state of her brother. Unfortunately, her lack of reply did not stop Kisumi from keeping going.

"I knew it smelled like sex in there. You guys really did it in the storage room? Is this why there is a huge bite mark on bucho's arm?"

"No way… The ONE TIME we don't listen, it actually worked?" Asahi buried them deeper.

Rin snapped again. It was just too much for him. He spun to strangle Mikoshiba, but the man was already taking off. He just got the time to catch a red flash of hair slipping away from the room.

Maybe they weren't the smartest to drop everything on him on the same day.

I'm so sorry, every time I try to write just about the two of them I just can't help myself to add Rin as well being the idiot he is. Literally everyone has written about SeiGou getting locked in a room or Rin being crazy angry at them. It's just too