A/N: Hello everyone ~ After writing my first oneshot about Yukio/Rin, I couldn't help myself writing this fic XD I love them so much so it needed to be done ;o; This story should be a short one, something like 5 chapters, but depending on the support I have it might be extending XD Also, it is rated M because I will write about incest, sex and some other happy stuff like that ~


Devil Beside You

Chapter 1: Dysfunctional Family

"Nii-san, get up."

Rin Okumura was sleeping; his messy jet-black head standing out from his bed with his pillow firmly held in his arms like a kid. Sighing, his younger brother shook him up, once again, yet Rin barely moved an inch.

"Are you serious?" groaned Yukio, giving up his usual composed self as he saw that even Kuro was still lying and resting peacefully on his tights. "You're sleeping more than 10 hours a day and you're still unable to wake up on time."

Yukio lifted up his blanket, chasing away the familiar of his older brother, and let running his left hand on his half-naked body. "When will you grow up, Nii-san?" said the youngest brother, before grabbing the tip of his tail violently.

"Yukio, you bastard." jumped out Rin. "Don't wake me up like that, it fucking hurts."

"I wouldn't wake you up that way if you woke up like a normal person. "

"Even so..." complained the eldest brother, massaging his tail. "What time is it?"

"7 o' clock." sighed Yukio as he looked at his watch, annoyed. "You have thirty minutes left before my class starts."

Getting up, Rin stretched himself and put his white shirt on. If he didn't want to be killed by Yukio, the exwire should hurry up like – right now. His little brother might seem the quiet type but he wasn't, oh hell, he wasn't. Since they moved in together, Rin had had a good overview of who was the exorcist – dark, aggressive, so violent he was afraid of teasing him sometimes.

"Just hold on a sec."

Childhood days were over, Yukio wasn't a cry baby anymore, and somehow, Rin missed it. Yukio coming in his bed (because he was afraid of the dark), Yukio clinging to him, Yukio calling his name. All of those gentle sides of him that had disappeared...

That's why the eldest brother ran to the kitchen, took away the bento he had prepared yesterday and gave it to his little brother, who was waiting for him, sitting on a chair, in their bedroom.

"Hey, four-eyed idiot." called out Rin with a grin. "Take this with you."

Yukio's blue eyes widened as he saw the colorful box and the chopsticks that his older brother were handing to him, surprised.

"I've noticed that you've been skipping meals lately... Something's wrong?"

Yukio smiled, adjusting his glasses. It was hard to hide things from him now that Rin was older. The exorcist had to be more cautious, it woud be a catastrophe if his cover was blown up yet it was hard to control himself when Rin was acting so... cute.

"No." blushed the youngest male. "But thank you, Nii-san."

"Don't mention it."

Feeling relieved, his older brother put his red case on his shoulder and headed to the exit. Rin was still dense, after all, thought Yukio as he followed him.

X

Classes had ended quite smoothly, if we took out the fact that Rin had fought with Bon, that Shura had barged into his class or that almost everyone hadn't understood the basics of creating a health potion – it could have been worse.

Yet, his day wasn't over. Yukio had still to meet with Mephisto who was currently missing; the director wasn't in his office nor in his favorite playground.

"What a pain."

Well, being a teacher at True Cross Academy turned out to be even more tiring as being an exorcist. He sighed but stopped his hurried steps as the exorcist caught sight of his older brother lying under the trees, outside, Yukio leaned closer to the window, with Shiemi.

It was bound to happen – someone else being infatuated with Rin... Yukio knew that his feelings were unrequired, and especially wrong, but that didn't mean they would disappear instantly with a magic trick.

"Do you like what you see?" stated a cold and mocking voice.

Rin was smiling. Shiemi was laughing. Leaves falling around them.

"Indeed, what a beautiful scenery." answered Yukio with the best poker face he could mutter.

At least, Rin was happy, that was all matter.

"I was searching for you." said the exorcist, facing Mephisto after he had turned himself around and averted his gaze from his older brother. "Where were you?"

"Oh you know, the usual, sneaking into secret rooms, spying on bad people." laughed the director of the True Cross Academy. "Anyway, shall you give me your reports on Rin Okumura?"

"Here?" frowned Yukio, pondering the fact that they were in a large corridor. No one should know that his brother was a demon, no one. "Aren't you a bit careless?"

"My bad, habits die hard." smiled Mephisto, before morphing himself into a dog.

The teacher sighed.

Oh hell, he was right.

X

When he came back home, Yukio was exhausted – and frustrated. He didn't know if Rin was already here or not but he locked himself in the bathroom. He needed to cool down, he needed to forget what he had seen earlier that day in school.

Why was he the only one to struggle so hard?

He opened the tap and entered the shower, cold rain running on his skin, wiping away the dirt and the sweat. What was going wrong with him? Usually, his mask didn't break so easily, usually he could handle his emotions – his anger, his fear. Shiro had trained him for that purpose at first before Yukio realized that he was raised as a weapon for the sake of Rin...

The young male rubbed his legs, his tights and then his crotch.

Since when had he felt like this? Since when his love for his brother had become so complicated – so disturbing, filthy and twisted?

He was rubbing harder – it felt wrong.

Yukio didn't know what to do. He was protecting Rin in his father's stead yet his emotions, dark thoughts and repressed feelings were going in the way. He was his little brother and at the same time, he was his teacher at school, and to add even more variables to the equation, Rin was a demon whereas Yukio was a human and an exorcist.

How could this be even more complicated?

He stood in front of the mirror, looking at his reflection, thoughtful.

"I'm stupid..."

The only thing Yukio was sure was that, no matter what, he wanted to see the smile of Rin.