Written for RinHaru Week 2014
Prompt: AU (Transformation)

Chapter 1

Chapter Text

The day had started off relatively normal. Haru had woken up, cooked himself some mackerel and gone off to the pool. In fact, Haru was planning to spend the whole day at the pool- maybe even the night if he could get away with it.

"Haru!"

Maybe Haru would be able to convince Coach Sasabe to let him stay after hours. It might take a little convincing to make the man believe that this time Haru wasn't planning to live in the pool after the last debacle.

"Haru-chan!"

Thinking about it, maybe he should just stick with the open hours. After all, Haru could always go and soak in the bath tub afterwards. There was mackerel at home too, which was a plus. There were a few new recipes he wanted to try out; sweet-and-sour mackerel, chermoula-marinated mackerel, even a mackerel risotto he had heard about.

"Haruka-senpai!"

Haru also needed to go to Sports ZERO and pick up a new swimsuit or two. Apparently a new design had come in, and as much as people liked to argue there was practically no difference between the suits, Haru knew otherwise. It was obvious; this one had two stripes at the base.

"Haru! Haru!"

The dark haired boy caught sight of Makoto wildly waving his arms, calling his name. With a sigh, Haru stopped swimming, standing up to face his best friend. Makoto stood in front of Nagisa and Rei, and was that the Samezuka team he saw? Haru furrowed his brow; Rin wasn't there. He waded forward, curiosity peaked and pulled the goggles off of his face.

"Haru-chan!" Nagisa waved his arms above his head, bright grin on his face, "You won't believe it!"

"What is it?" Haru cast a glance around, confused to see his team next to Samezuka; maybe they wanted to race?

"Woah, Haru, is that really you?" A small figure burst forward past Makoto.

Haru blinked.

In front of him, grinning like a maniac was the Rin that he remembered before the boy moved to Australia. Rin was a kid. Here. In front of Haru. Kid Rin. Little Rin. Baby Rin.

Haru kept blinking.

"Somehow, Rin turned into his younger self," Makoto was explaining, but Haru was only half-listening, busy staring at Rin in disbelief, "Momo says it has something to do with some weird fruit he bought,"

"Magical fruit!" Momo interrupted, grinning, "The lady who sold it to me said it could do magical things,"

"By all accounts, it's completely illogical," Rei pushed his glasses back onto his face, "It shouldn't be possible,"

"But it is, Rei-chan!" Nagisa was bouncing up and down on the balls of his feet, "Rin-chan turned into a little kid!"

"I'm not a little kid!" Rin glared, before declaring proudly, "I'm 12 years old,"

"…" Haru didn't know what to say.

"He doesn't remember anything after the age of 12," Makoto continued explaining, his face turning apologetic, "He says he doesn't want to stay at Samezuka,"

"Haru, I want to stay with you," The younger Rin gave him a wide grin, "Pleeeeease?"

"Me?"

"Pleeeeeease?" Younger Rin clasped his hands together, sticking his bottom lip out, "Pretty, pretty, please with a cherry on top?"

"You don't have to, Haru," Makoto said, "We can find someone else to look after him until we figure out how to fix this,"

Haru hesitated, "…Fine,"

"Yes!" Little Rin grinned, "This is going to be awesome!"

Oh boy, what did Haru get himself into?

I wonder what antics 12 year old Rin and his babysitter are going to get up to in this multi-chaptered fic? Any ideas?