This story uses the anime plot as well as the anime dubbed names since I have not been able to see the subbed and the versions I do find are terrible.

But I liked the English VA's a lot so I'm not really looking ^_-

I still have a lot to do with my other ENORMOUS co-story, but I don't think it will be as long as the others before I update this one. I don't plan on it being very long. It will still be a while though. I've also never written for Ao No Exorcist before but I've had this idea for a long time and I just really wanted to put it 'on paper'.


For My Brother

Chapter 1: The Illness

Yukio woke up with the sun, dressing for the day and finding his brother still asleep as always, the covers half off of him and dragging around the dirt as he snored. He sighed. Rin really hadn't grown up since… well, ever.

He packed away his papers for class and headed out after some breakfast just as the sun made it's way high enough in the sky to be unguarded by the trees. Rin would be up in an hour or two- if he woke up on time today. That was his own problem.

The class was silent.

Yukio was standing at the desk, pointing out the different characteristics between demons and familiars. In some cases there was a fine line as temple sprites could often take on either form. The scratch of pencils was the only noise to be heard until the bell rang.

"Where the heck is Okumura!" Bon hit his hands on the desk, looking around as if the demonic teen would somehow burst out of the walls, waiting for his chance to scare the crap out of him.

Yukio pushed up his glasses as he made his way to the door. Rin was going to get extra work for sleeping through class. "Likely he stayed up all night reading manga and decided school wasn't as important."

"Damn it! I hate that laid back attitude of his!"

Yukio couldn't agree more and he left the other students to talk among themselves.

On a whim, Yukio decided he'd pick up a few things for their meals. They were running low with how much food tended to be consumed for his rather meager paycheck. He had to buy some more ammunition for his guns as well, so he stopped by the shop on the way back.

Inside the dorm, Yukio dropped the plastic bags on the floor before going over to his still unconscious brother. "Hey, moron. How do you plan on being an exorcist if you can't even make it to class?"

Rin snored his answer.

Yukio sighed. "Sometimes I really don't know if you're serious about this." Sitting down and the table and dropping his work bag, he took out the papers he would need for the lesson tomorrow so he could work out a homework sheet. Maybe they could have a test as well, which would teach Rin he couldn't just come and go as he pleased.

It wasn't until he yawned and looked at the time did Yukio realize how late it was. Almost on cue, his stomach growled as well. Pushing his glasses up once more, he turned to Rin. He sure can sleep.

With the pencil still in his hand, Yukio went over, prodding him on the cheek with the eraser end. "Come on. Aren't you even going to get up to eat?"

Another snore but this time Rin shifted his head just the slightest and Yukio caught a glance in the low lamp light of how pale he was. "Are you sick?" He put a hand to his forehead and quickly took it away.

"Ow, ow, ow, ow." Yukio was on his feet, shaking his hand. He had to blow on it. There was red, raw skin where a healthy layer had been just seconds before. He looked back at his brother, a bit of worry there now. Maybe he was sick. Why the hell did it have to burn his hand though?

He left the room to go get some bandages and hunt down an electric thermometer so he wouldn't blow up a glass one if Rin really was that hot. He didn't know how demon fevers worked and Rin hadn't been sick since he'd grown into his powers.

Once he lightly covered the minor burn and eventually found a thermometer, for some reason in the drawer down in the kitchen when he went to grab a glass of water, he went back into the bedroom. Careful, and with his bandaged hand this time, Yukio moved Rin's head to the side and stuck the device in his ear. It beeped a few times before it said it was done.

Yukio leveled a gaze at it, his annoyance growing. 'High'. How informative. He tossed it on the shared desk before letting out a sigh and looking back at Rin. He bent down, shaking his shoulder lightly.

"Rin. Are you okay?"

No answer. Of course.

Yukio left the water near the bed where it wouldn't get stepped on before turning towards the desk once more and flipping the light off. He'd check him in the morning and if he wasn't better he'd go ask Mephisto.

Morning came and Yukio put on his glasses, looking across the room at the bulge on the bed that told him that nothing had changed. He pushed the sheets back, using the bandages as insulation against the heat as he put his hand back on Rin's forehead. He didn't even need a second for the warmth to travel through the bandages. It didn't hurt this time at least.

That sent Yukio on a trip to see the headmaster of the school. Mephisto, it seemed, was not an early riser and he had to wait near an hour before he was allowed to see him, a small green hamster watching him all the while from the desk. Mephisto was almost as strange as Rin in some aspects.

"Hello. What brings the best teacher in the school here?" Mephisto came in, a coy smile on his face and a confident gait in his steps as he sat behind the padded chair and started at him from across the large desk. The small hamster made it's way over to him as if the creature knew it was his owner. With Kuro as an example, Yukio had to think that maybe it was some kind of demon.

"It's Rin. He seems to be sick and he hadn't woken up in over twenty-four hours so I'm worried. I didn't know demons could get sick."

There was a moment of silence while the headmaster just started at him before bursting out laughing, his chair sliding back an inch as he leaned back into it. His wails likely made it past several doors and lasted nearly twenty seconds.

Yukio wasn't as amused.

"Demons get sick? My boy, even you know that demons don't catch human illnesses. They have very strong immune systems. Maybe that cold virus that doesn't seem to react to any treatment has gotten a few of the weaker ones but I'm sure Rin isn't that weak."

"Then what is it?" Yukio unwound the bandages and showed off the reddish skin beneath it. "He's burning up and he woke wake when I try. I, myself, don't know what's wrong with him and I thought you might."

That changed Mephisto's expression, the careless humor now consumed by serious contemplation as he folded his hands together and stared at the wound.

"I have to assume it's his fire," the headmaster spoke after a minute. "It's somehow burning inside his body." Then the smile was back and whatever else had been there before was masked behind it. "How about we go see him? That'll help me answer your questions."

Yukio stood, re-bandaging the hand so he'd be able to touch things without causing himself pain. It also proved a decent enough shield against the fever.

They went through the rooms that were immaculate, due to his brother not having time to wake and mess everything up. Yukio opened the door to their bedroom and made sure he went in first, throwing his bed sheet on the bed, embarrassed at himself for not having made it before he'd walked out.

Mephisto didn't need an invitation, slipping over to Rin himself. His own hand was gloved and he was more than sure he wouldn't be harmed. After feeling the same heat and poking at the boy, moving him a little and getting no reaction, Mephisto stood. "Hm. The sword is sheathed, correct?"

"Ah, I'm not sure." Yukio hadn't had reason to believe it wouldn't be. Instead of letting the headmaster see for himself, he went over to the closet right next to Rin and took out the cloth bag. He opened it, but the sword was shut as it normally was. He closed the bag back up. "It is."

"Then it's even more strange. He's using his flames without his power being released." Mephisto placed a finger on Rin's chest. "And he's using them internally. I've never heard of a demon doing that. I have to assume it hurts."

"So what can we do to help him?" There a slight ting of hysteria in Yukio's words. Something was attacking Rin and of course the idiot had somehow found a way for it to be his own power. Yukio could kill a demon but he couldn't do anything to protect Rin from himself. "I've never heard of that before. How is it even possible? Is the sword broken again?"

"No. No. If it were it wouldn't be just this small leak, and we'd know." Mephisto stood as if thinking, looking down at Rin as if he were a new toy that was able to talk when it wasn't supposed to.

This time the silence was a lot longer and the words were spoken quietly, almost dully and half skeptical. "Maybe his life is in danger."

Yukio waited in the increasing silence but there was no further explanation. "What?" he finally asked.

"Some powerful demons, when their life is in jeopardy, call upon a greater power. It is like humans. No human, or demon for that matter, uses their brain to its full capacity. Not because we don't want to but because we physically can't. With strength, it can be near doubled if not more of what it should be when someone's life is in danger. Maybe your brother thinks his own is, or it is somehow inside his body, and the power sparked up as a way to protect him."

"That doesn't' make sense. Rin has been in danger before and his power didn't react then."

"I said it was a possibility. Besides, there way always someone with him or close by before, was there not? That's not really having your life in danger when your comrades can come to your rescue."

Yukio wasn't going to say anything back to that but he hadn't ever seen Rin on his own, as Mephisto pointed out.

"So what do we do?"

"We? Well, I'm not exactly sure myself what he's doing." With seemingly no care at all to Rin being hurt or far exceeding the body temperature of anything living Yukio had seen before, Mephisto simply picked him up. "I suppose we just try to wake him and see what he had to say." He dropped him right back on the bed.

"Hey!" Yukio defended. "What was that for?"

Rin moaned and moved. It was the most Yukio had seen him do since the night before last. Mephisto was able to hide a dark, happy smile between the brother's distraction and the sound.

"I was waking him."

"I see that. You didn't have to be so rough about it though." Yukio pushed his glasses up and stepped forward. "Rin, are you awake?"

"Ohhhwwww…" Rin winced behind closed eyelids. The word was barely distinguishable from a sound. The rasp it held and the faint trail of shimmering air as he opened his mouth didn't go unnoticed.

"Rin, where does it hurt?"

Rin didn't answer again though, just wincing once more and making a motion as if trying to open his eyes but the lids were to heavy. It was a good minute or more and a few deep breaths before any of them moved. "E'rywhere."

"Rin, you have to stop using you're power. You're hurting yourself." Yukio wasn't going to risk his forehead but he safely put his hand on Rin's shoulder, Mephisto standing back to watch the brothers.

"Can't." It took more effort that seemed to stretch on before, finally, he was able to open his eyes. Yukio's first reaction was to jump back, his hand half reaching for his gun while he fell on his butt in his failed attempted.

Yukio let out a few quick breaths while Rin started at him, speaking but the words were more… read off his lips than they were heard. "Wha's wrong?"

"Mephisto, sir, what's wrong with him?"

"Hm." Once again the headmaster bent his knees to better to see, a curious expression on his face. "It look like it's just a wound. His power hasn't changed at least so I don't think it's anything more than what it appears. How the blood vessels in his eyes broke though, I don't know."

"Huh?" Yukio watched as Rin put a hand to his face, over one of his eyes while the other seemed to close with the strain of effort. "I… don't… know… what… the… hell… you… guys… are… saying."

It took near half a minute for Rin to get his full sentiments across. Yukio stood back up, trying to see why. Rin's breath's seemed to be shallow. It was likely hard to talk while not being able to take in enough air. Yukio had to wonder if maybe the flames worked like normal ones and he was somehow burning off the oxygen.

"You have a fe- You're using your power on yourself somehow. It seems you're hurt? Maybe? I was hoping you could tell us." Yukio refused to be afraid of his brother simply because his eyes were now blood red. It really didn't help though.

Rin just shook his head. "Didn't… even'do… anythin'."

Yukio knew that. The academy had been quiet for the last few weeks and they hadn't gone on a mission since that bear demon in the forest. Needless to say, the bear demon was no more, but neither was the forest. "I know that. Or at least, I know what you should and shouldn't have been doing. Did you go anywhere strange or do anything different?"

Rin shook his head slowly, his hand falling back to his side and his remaining eye falling closed. "Tired."

"Wait! You can't go back to sleep." Yukio reached over, shaking Rin so he wouldn't pass back out. "You haven't eaten or had anything to drink in over a day. Stay awake and try to get something down, please?"

Either Rin was tricking him or the idiot could only pull off things he wanted to as he smiled at him. "Always… room… food."

Yukio had to let out a small laugh of his own as he stood up. "Good. I'll get you something then. Don't fall asleep." He quickly made his way out of the room, wondering if Rin could eat soup.

Mephisto sat on the bed, folding one leg over another once he was alone. The small hamster made it's way down his arm and more or less tumbled end over end down his back. It poked its head up, unharmed, from the sheets before running over them and resting on the boy's stomach as be breathed.

'This is definitely dad's power. He's going to kill himself.'

"I know, and what a shame that would be. I always pictured some great battle. Oh well. It seems our little brother isn't as in control of his powers as he seemed. Maybe they're burning him from the inside out."

Amaimon turned his hamster head back to his Mephisto. 'Why didn't you tell that other boy that?'

"Why should I? If that is what's going on, there's nothing we can do. Besides, Yukio is talented. If he can find out what's wrong I'm sure he can take care of it on his own." Mephisto stood, offering his hand so his little hamster brother could run onto it before being placed back on his shoulder. "I saw we leave them be for now and see how things turn out."

Mephisto was gone when Yukio came back in with the soup. He looked around for him but his focus right now was Rin so he let his disappearance go and sat on the side of the bed, shaking his brother again. "Rin, I told you not to fall asleep."

"Mmm." Rin seemed to try to open his eyes again and failed. Yukio sighed, getting behind him and helping him half sit, though it was clear Rin wasn't holding up any of his own weight.

"Here. Open up."

Rin opened his mouth obediently and Yukio fed him as much as he could before Rin just refused to eat anymore. He finished maybe half the bowl. "This reminds me of when we were children. Dad always used to take care of us because whenever one of us would get sick, so would the other. Then when we were better, he'd always catch it." He couldn't help a laugh and saw a smile on Rin's face as well.

"Yeah… old man… never… figured… out to… stay away."

Yukio was pretty sure that dad knew what he was doing, even if it did make him sick afterwards. That was just the kind of man he was. "If I recall, you were always the one that got me sick."

"Not my… fault you… lived in…. the house. Can't get… germs if… you don't…get out."

"I went out. I just didn't hang in alleys and around the type of people you did."

"Geek."

"Punk."

Yukio was annoyed at Rin for the light breaths that he knew were laughs aimed at him before he smiled and let it go.

"Well, you better not give me this. I don't even know what you have right now." But better to let him think he was simply ill. Yukio was going to find out what was wrong with him and he was going to get him some help along with going to class that started in an hour. He sighed.

"Well, time to get down to business."