I just really wanted some Rin/Kou brother/sister fluff. Featuring Kou/Seijuurou, NagiRei, and HaruRin. Hope you enjoy.

Rin had been ignoring Kou since he returned from Australia. He had been mean and stand-offish for weeks. Although it hurt his sister's feelings she hadn't lashed out at him, sensing something else was wrong with her brother. Yet, everyone has their limits and when Rin tried to act like a protective older brother when he'd seen her and Seijuurou flirting the pent up emotion exploded out of her.

"You aren't allowed to say that, you jerk!" she screamed at him, catching both Rin and Seijuurou off guard. Rin's comment had only been a pretty harmless one about Seijuurou keeping his eyes off his sister, but for whatever reason, it had set off something inside Kou.

"You can't just leave without any explanation, ignore me like I'm some sort of stranger, and then expect to pull the big brother card!" she seethed. By this time all of the swimmers were staring at her.

Rin's eyes widened and he opened his mouth to say something but Kou cut him off before he could. "I hate you. You won't even look at me and you try and act like my big brother. You are the worst! That's not how you treat family!" She huffed in annoyance and finally became aware of the utter silence her outburst had caused among everyone else around them. She glared at her brother one more time before she stormed out of the building.

She walked as far away from Samezuka Academy as she could before she finally collapsed onto a bench and sobbed into her hands in frustration. "Damn it, why did I do that?" she hissed to herself. After a few minutes her sobs quieted but she stayed rooted the bench, staring blankly at the ground.

"Gou." She looked up in surprise to find her brother there, staring at her with an expressionless face.

She narrowed her eyes at him. "What do you want?" she hissed.

Rin sighed. "I'm sorry."

Her eyes widened. She had not really anticipated her brother following her and she definitely had not expected him to apologize. Nevertheless, she wasn't ready to stop being angry at him. She grunted in reply.

Rin's expression softened as he sat down next to her. "I shouldn't have ignored you," he breathed.

Kou nodded in agreement. "I know that."

He chuckled lightly. "How about I buy you an ice cream?"

Kou glared at him. "I'm not hungry."

Rin sighed, stood up, and offered her a hand. "Just stop being stubborn and come with me. We need to talk."

Kou scowled but her curiosity got the better of her. She really did want to find out what had changed her brother so much. She pushed herself off the bench, ignoring Rin's hand. "Fine."
They walked to the ice cream shop in silence, neither sibling even daring to meet the other's eyes. When they arrived Kou sat down at a table and allowed Rin to order.

"Strawberry is still your favorite, right?" Rin asked, as he handed her a strawberry cone. Kou blinked in surprise that he still remembered and nodded.

"Thanks," she mumbled. Rin offered her an uncertain smile.

"So... why did you decide to be the manager of the Iwatobi swim club?" he asked.

Kou narrowed her eyes at him. "No, I'm asking the questions," she asserted. Rin rolled his eyes, but didn't argue. "Why did you leave to go to Australia?" she began.

"I already told you all. I want to be in the Olympics," he replied simply. Kou huffed. She knew there had to be more to it than that, but she sensed he wouldn't tell her even if she pried.

"Fine. Then, why did you come back? Did you think you weren't good enough?"

Rin fell silent and grimaced. "I knew you were going to ask that question," he grumbled after a moment.

"I want an answer," Kou hissed.

Rin glared at her, but his expression softened when he realized how concerned his sister really was. He ran a hand through his hair. "I'm pathetic."

"What?"

Rin groaned. "I came back because swimming didn't really matter if I wasn't swimming with him." Kou blinked, not comprehending him.

"I don't understand," she admitted.

Rin scowled. "I moved to Australia because I wanted to make dad proud, but I realized I didn't care about swimming anymore without..." His voice trailed off and he blushed, shaking his head in embarrassment.

"You... you missed Haru?" Kou breathed, staring at her brother in surprise. "Then why didn't you act like it? He would swim with you if you just didn't act like a jerk!"

Rin gritted his teeth and didn't answer. Then, a strange thought entered Kou's head. It wouldn't really make sense but, maybe...? "Onii-chan, are you in love with Haru?" she asked softly, voicing her thoughts aloud.

Rin's face remained emotionless, but he did nothing to deny it. Kou's mouth dropped open. She wanted to ask more, but it was clear her brother was not going to say anything else about the topic. Rin pushed himself out of his chair, gazing blanking at the table. "I should probably get back before curfew, Gou."

He went to leave the building, but Kou jumped up and wrapped her arms around him. "Onii-chan," she muttered. Rin stiffened, but allowed her to hug him for a second before he pried himself free.

"You won't tell anyone about this?" he asked softly. Kou nodded breathlessly and he offered the faintest of smiles. "I'll come by for dinner sometime this week. Tell mom."

….

Two weeks later Kou was still shocked by the information her brother had given her. She had seen him a few times since, but he hadn't said anything about his supposed feelings for Haruka. Whenever Kou tried to bring it up he would quickly change the subject.

Kou was currently searching for Haruka and Makoto to ask about an idea she had for the swim club. She turned a corner and saw Haruka standing there staring blankly at his companion like always, but instead of Makoto, Haruka was with a girl. Kou backed around the corner to listen to the conversation, her interest piqued. She knew eavesdropping was impolite, but she didn't really care.

"Um... Nanase-kun, I was thinking we could maybe hang out this Saturday," the girl suggested shyly.

Kou gasped and covered her mouth. Was Haruka being asked out on a date? Why did she feel so angry at the girl? She peeked around the corner to see his reaction but his face was still a mask of indifference. "I think I'm busy,"he answered flatly.

"Oh, well, I was hoping we could go to the beach," the girl interjected. Kou bit her lip as she watched Haruka's eyes glitter. Somehow the girl had known the magic words. There was no way Haru would turn down water.

Sighing, Kou walked in the other direction. She had no reason to be mad at Haru, but she realized she was anyway. Ever since Rin had confessed her feelings for him she had been, unwittingly or not, trying to figure out ways to get them together. Of course Haru had no idea of how Rin felt, but Kou still didn't want her brother to get hurt.

"Gou-chan! Gou-chan!" Nagisa called as he dragged Rei down the hallway. "Want to go to the mall with me and Rei this weekend?" he asked excitedly. Rei pushed his glasses up his nose, and offered Kou a smile.

Kou scowled at the name Nagisa called her yet knew saying anything about it would be useless. "How about we go to the beach instead?" she suggested.

Nagisa grinned. "Yeah, that'll be really fun, right, Rei-chan?" he cried as he dangled off his flustered friend.

The next day Kou met Nagisa and Rei early and they headed straight to the beach. While Kou sat watching on a towel, Nagisa happily dragged Rei into the water, ignoring his friend's protest. Kou laughed at them in amusement, before sitting back and trying to relax. Her eyes roamed the beach, but she didn't see any sign of Haruka. She decided to read her book until Nagisa interrupted her.

"Haru-chan!" he cried. Kou looked up and noticed Haru arriving with the girl from earlier trailing behind him. Nagisa made to dash after them friend, but Kou stopped him.

"Nagisa, Haru-kun is on a date," she interjected.

Nagisa's eyes widened. "Really? Why didn't he tell us?" he asked in surprise.

"Haru-kun has a date?" Rei mumbled in bewilderment. He watched as Haru walked down the beach, threw his clothes off, and left his supposed 'date' alone in the sand as he dove into the ocean.

Kou shrugged. Nagisa reached over and grabbed Rei's arm. "Dates are fun? We should go on a date sometime, Rei-chan," he grinned. Rei nearly fell backward as he sputtered, totally unable to tell if Nagisa was being serious.

"Gou," A voice barked. Kou nearly jumped out of her skin when she noticed her brother staring at the three of them from a few feet away.

"You can't sneak up on me like that... and I told you to call me Kou," she quipped. Rin snickered.

"Rin-chan!" Nagisa cheered as he raced forward to greet his old teammate, leaving Rei blushing in the sand. Rin scowled at him.

"What are you doing here?" he asked his sister.

Kou tried to position herself so her brother wouldn't notice Haru. "Oh, we're just hanging out at the beach," she answered.

"Is Haru here?"

Kou tried to say something but Nagisa cut her off. "Yes, he's over there!" Kou was shouting inside her mind for Nagisa to shut up, but the boy didn't even notice her sharp glare. "We can't bother him because he's on a date," Nagisa finished with a smirk.

Rin's eyes widened and his gaze fell on where Haru was now standing up in the water. The girl he was with playfully splashed him, before throwing her arms around his shoulders. Kou felt like she was watching a trainwreck. When she turned back to where her brother was standing moments before she found he was already half way down the beach. Not even her desperate calls of his name caused him to glance back.

….

Kou texted Rin at least ten times a day but she never got a reply. It frustrated her beyond measure. For one thing, her brother was acting like a toddler. Surely, he couldn't have expected Haru to return any feelings when Rin had blatantly ignored him for months. Despite this, Kou was still angry at Haru for hurting her brother.

Kou knew she was doing something stupid and breaking a promise, but she wanted her brother to reply to her and stop acting like a baby. She pounded on the door of Haru's house. "I know you're home! Get out of the bathtub and open the door!" she shouted. She was beginning to consider the back entrance when Haruka finally revealed himself, a bath towel wrapped around his neck.

"Matsouka... what do you want?" he asked dully. Kou could have wrung his neck, but tried to cool her temper.

"Are you still dating that girl you went to the beach with a few weeks ago?" she asked sharply.

Haruka raised an eyebrow, wondering where this was going. "It wasn't a date," he responded indifferently.

Kou groaned and balled her fist. All this trouble over something that wasn't even a real date. "I need you to talk with my brother. Please. He's driving me crazy," she hissed.

Haru's face didn't betray any emotion, however, his eyes sparkled slightly to indicate she might have caught his attention. "Why?"

"Because..." Kou took a breath, wondering if it really was worth it to betray her brother's trust for this. 'Too late to rethink now,' she reasoned. "Because he's in love with you."

Haru's eyes widened, but he didn't say anything. Kou didn't wait for a response. She turned and hurried away, leaving the boy to his thoughts.

It didn't take long for Kou to regret her decision. Rin continued to ignore her texts and Haruka didn't make any indication he had seen her brother at all. So, when Kou found Haruka standing outside her door she was extremely surprised.

"You have ten minutes to get dressed into something nice," Haru said, in his usual monotone. Kou raised an eyebrow.

"What are you-"

"Hurry," he interrupted. He turned her around and pushed her inside. "You don't want to be late."

Kou was very confused, but her curiosity got the better of her. She quickly pulled on a yellow sundress and tied her hair up in a messy bun before meeting Haru downstairs.

"Is this what you want?" she asked.

Haru shrugged and walked out the door, a quick glance over his shoulder the only indication he expected her to follow.

Haru led her onto a train and ignored all of her rapid-fire questions as he stared blankly out the window. Eventually, she gave up and sat quietly until he finally got off at a stop downtown. She followed Haru through the streets until he eventually came to stop in front of a nice restaurant.

"Haru...?" Kou breathed before she was pushed into a tall figure. Flustered, she looked up to see Seijuurou, looking equally as confused as she felt.

"Kou?" he mumbled before his face split into a grin. "You look pretty," he complimented as his face turned pink.

She felt her own cheeks heat up. "Uh... thank you. What are you...?" Her eyes widened when she noticed Rin standing behind Seijuurou, smirking.

"Onii-chan!" Kou called. Rin smiled at her in earnest. "What's going on?" she demanded.

Rin shrugged. "Just returning the favor," he replied with a smirk. Kou raised an eyebrow in confusion only to see her brother take Haruka's hand, lacing their fingers together.

Kou laughed and smiled warmly at them, the blush on her face growing hotter. Seijuurou was watching Rin and Haru in confusion, but neither seemed to mind.

"Have her home by eleven," Rin called over his shoulder before the pair walked off, hand-in-hand.

So, that was it. I can't stop writing Free! fluff. I thought maybe I should upload one and see how it goes. I really like Gou-chan. Free! wouldn't be the same without her. I hope we get some brother/sister fluff in the show. Hope you enjoyed this. Shoot me review if you can.