Rin was developing some nasty habits. Yukio heard himself sigh as the door to their bedroom opened slowly. A figure crept in slowly through his side of the room. Yukio ignored his brother sneaking in at such a late hour, for now. He had a test to do in the morning and give one in the afternoon so he was in no position to be arguing with Rin all night.

It's not like Rin hadn't snuck out before. He did it plently of times back home and their dad had delt with it by just locking the poor bastard out until he shouted an apology. Back than, Yukio didn't have to worry so much over his older twin. Rin would get into some fights over trivial things and come out with only a few bruises and scratches. Course, all that had changed. Now, Yukio couldn't stress enough how dangerous the world was for his brother. Every corner could lead to certain death because of the fact that Rin was the son of Satan and have demonic powers of his own, along with the fact that the fool wanted to be an Exorcist also. There were fellow Exorcist, who still held a grudge against that terrible night of their birth, that would love nothing more than to see Rin burned on a cross! Rin knew all of this too well, yet still had the lack of sense to go out these past few days of every month to fuck around with total strangers!

"You can't keep doing this." Yukio said one saturday where neither teen had a class to go to. Rin was in the kitchen, frying some eggs and bacon for them, while the little famaliar, Ukobach was serving white rice and fruit.

"You mean your gonna start getting off your ass and help me and Ukobach out in the kitchen?"

"I'm not talking about that!" Yukio snapped. He paused than said, "You don't want me to get better at the one useful talent you have, do you?"

"I have other talents besides cooking, four-eyes!" Rin snapped as he slammed the plate of food on the table causing Ukobach and Kuro to jump. Yukio only half-smiled, as much as he enjoyed pushing Rin's buttons, now was not the time.

"I meant you sneaking around at night, Rin. It's not safe." he said as his big brother sat down across the table from him. Rin frowned, "I told you that am fine. I haven't ran into any trouble yet."

"Yet." Yukio repeated. Rin growled, "It's not like I can help it! These stupid demon urges drive me crazy! I feel like humping everything when I'm in heat!"

Yes, Rin Okumura was in heat.

He started a couple of months back and it freaked them both out. Melphisto had to step in and explain everything, " You see boys, it's simple. When a demon reach that special time in their lives, their hormone levels become 10x higher than a human and want to mate every hour for a short amount of days." he spoke calmly and slowly as if the Okumuro brothers were 5 years old, " 'Mating' is what mommies and daddies do to make you!", or like they were retarded. From than on every month Rin would get the urge to sleep around with anyone willing on the street. Yukio couldn't finish the list of dangers waiting for his brother whenever he walked out that door before, and now this? Sometimes he wish he could just put Rin in an unbreakable, human-size, hamster ball! Anything if it made him sleep better at night knowing his brother was safe and sound. Yet, no such thing have been invented as far as he knew, and knowing Rin, he'd probably find someway to break it!

"Look, I'm 16. I been through a bunch of shit so far and survived, Yukio. Me getting laid isn't gonna end the world!" Rin said as he gulped down some of his rice. Yukio frowned at him, "Rin, I'm only concerned! What if you catch a disease or get some girl pregnant?" he argued. Rin rolled his eyes, "Relax. I use a condom." he claimed, resting his elbows on the table. Yukio ignored his brother's lack of table manners and continued, "Condoms break, dumbass!" Yukio shouted and stood up, "Your so irresponsable that I'm surprised you can even remember to bring them, much less buy them!" Rin tsked, "Your just jealous that I lost my virginity before you. Even though you got a flock of fangirls waiting to suck your dick. Clueless bastard."

Yukio blushed and straighten his glasses, "It's not like that and I do not have fangirls!" he claimed. It was Rin's turn to stand up, "Clueless bastard!" he repeated, "All those girls following you home every day and practically giving hints that you can fuck them and it's 'not like that'? Your selfish, Yukio!" Yukio was taken back by that, "Excuse me?" Rin growled, "Yeah! You can get a pretty girlfriend anytime you want and all I get is some prostitutes across town!" Yukio gaped, "P-p-prostitutes? Rin, you been going to prostitutes?!" Rin rolled his eyes again, not believeing how smart Yukio can be but can also be so naive sometimes. And people said he was the dumb twin.

"Yukio, please. Who else would I get to fuck with? I can't hook up with any of the girls here at the academy because they either think I'm a creep or they might find out I'm a demon and tell the whole world!"

"But how are you hiding that fact from the...prostitutes?" That word sounded so dirty to the younger brother. Rin only shrugged, "Most of them are high or seen stranger shit than a kid with a tail." Yukio had to seat back down again, trying to retain the fact that his brother is letting, not just strangers, but people who have an even greater chance of passing a sexually transmitted dieases, touch him was too much for now. Rin sighed and took up his plate, "I'm finishing in my room." he announced and turned around. Yukio looked up, "Wait! We're not done talking!" but Rin was already walking, "I am!" he yelled back when he suddenly paused at the exist and turned back around to Yukio, "Your Satan's son too but you haven't gone through a quarter of what I been putting up with. I'm tierd of you treating me like a kid and judging every decision I make! Your not dad, Yukio. So stop sticking your nose into my business and mind your own, dammit!" with that he left, leaving Yukio alone again.

That following night, Yukio was coming home from a mission up town. Reports were going around about ghoulish hounds stalking a neighborhood and attacking anything on the streets at night. Yukio had shot at least 60 of those possesed things before convencing the neighborhood the dogs all had rabies, which explain why they were acting so vicious and demonic. He was glad to get to the old building so he can flop on his own bed before dawn. However, when he reached for the door knob to the room, a giggle was let out. Yukio paused and heard muffled talk and thuds. 'Someone is in there with Rin.' Yukio's heart rate went up as he turned the door knob slowly and quietly. He stepped in silently across the room and crouched down by the door seperating their rooms. There was no yelling, or glass breaking, so maybe it wasn't an assassin of some kind that broke in their house to get Rin. Yet, Yukio wasn't sure, so he pulled one of his guns out, just in case. More muffles and the sound of the bed creaking made Yukio too curious, so he slid the door back by just enough to peek inside.

"Ooohhhh God, Rin~!"

"Say my name louder, Shiemi."

"Rin~! I never felt this good before~!"

"Fuck yeah! I'm going to make you see Amahara tonight!"

"Oh God, I can see it! Yes~! Harder! Harder! Rin~!"

Yukio quickly shut the door and got out the room as fast as possible. The rest of the night he spent it in the dinning hall with Kuro sleeping on his lap. Rin must have locked the poor demon cat out of their room earliar. Yukio couldn't sleep at all. He's mind was racing with confusing feelings and regret. He was jealous, of course, but not of Rin.

That's what scared him.

Morning finally broke, sunlight shined through the cracks of the windows and Yukio groan. Ukobach was up and pulling out pots and pans which made Yukio's headache grow even more. Kuro woke up and jumped off his lap when the younger brother began to shift alot. It stretched it's little body and meowed up at him. He was pretty sure it was saying 'Good Moring' to him, but he couldn't hear the cat-demon's thoughs yet like his brother. Yukio just rolled on the long stool and laid there. Kuro tilt it's head and meowed something to Ukobach, who only shrugged and continued to make breakfast for the house. It finished quickly and set the tray of food for both brothers at the table. Yukio didn't feel like eating because he still felt the nause from last night after discovering Rin and Sheimi were fuck buddies now.

Yukio wanted to shoot somene.

"Morning, everybody."

Like Rin.

"Why are you sleeping out here?" Rin asked strolling over to the table as if he hadn't screwed one of the most purest girls Yukio ever met last night. Yukio heard some dumb questions from Rin before, but this was pushing it.

"I just felt like it." he said, staring up at the ceiling. Rin only shrugged and sat down at the table and started eating, after thanking Ukoback for the food first. Yukio didn't sit up or eat anything. He didn't want to be rude to the stove demon but he really didn't want to dine with Rin right now.

Rin either didn't notice or cared about Yukio's strange behavior and finished his meal. He scooped out some left overs for Kuro, who eageredly waited for it and gulped it all down. Rin got up and left.

That was it. No apologies. No explantions. No Shiemi. Yukio wondered if she left earlier and he just didn't notice. Yukio rolled over to lay on his side. He wanted to throw up but not really. Tears fell from his face and he didn't know why.

The rest of the morning, neither the twins said anything to each other or sat by each other, or ate lunch together. It was very strange, since everyone, Exorcist student or regular student, knew the brothers were practically in seperatable.

"What's up with you and Yukio?" Renzou asked as the trio of monks walked up to Rin at lunch period. Rin ate his lunch grumbly but didn't complain on the company.

"Nothing." he said between eating. Renzou, Konekomaru, and Ryuji looked at each other,

"But I haven't seen you guys talk to each other all day. Did something happened?" Konekomaru asked out of concern. Rin frowned and growled, "We're twins but not glued to the head, guys! Jeez! Yukio just wants space and I'm giving it to him." he huffed and went back to eating his lunch angryly. Konekomaru would have pushed a little more but Ryuji stopped him, "Forget it. Let's just leave this dumbass alone. He can solve his own sibling problems." The trio left and Rin stopped eating. He stared at his bento and wanted to punch something.

That following evening was intense. Everyone sat far away from Rin and stayed on Yukio's good side as he lectured the class. Shiemi didn't show up to class, perhaps out of shame or whatever. Rin act like he didn't missed her but the fact that his tail was drooping said other wise. Yukio acted like everything was fine and handed back last weeks homework, but the fact that he slammed it on Rin's desk said other wise. The two mostly shot death glares at eachother ever chance they got through out the entire session which made the class almost unbearable.

What seemed like forever, class finally ended and everyone practically ran out of the Okumuras' way. Yukio stayed at his desk, pretending to be busy grading and Rin slumped out of the room, but not before kicking the side of Yukio's desk. Yukio chucked a stapler at his head, but Rin ducked and left. Outside in the hallway, Rin leaned against the wall and sighed, why was his life so fucked up?

"You okay?" He's ears perked and he looked up at Ryuji walking up to him. The teen frowned at him like always but concern was in his eyes. Rin shrugged, "You won't understand." he said. Ryuji raised an eyebrow, "Try me."

Yukio didn't go straight home. He went over to Mephisto's office, hoping the purple demon was there. Two knocks earned him permission to come in. When he stepped in, the room shifted to a fun house full of posters, shelves filled with anime DVDs and manga, figurines and junk food. Mephisto was sitting on a huge pink bean-bag in front of a huge flat screen, playing video games. Yukio wasn't fazed and bowed respectivly to his superior who just reached another high score on Mortal Combat. Mephisto grinned at him, as if he already knew what the young Exorcist wanted to talk about.

"Good Evening, Yukio! Want to play around?" A controller float above Yukio's head. He took it but didn't sit down with the older Exorcist. "I wanted to discuss about Rin's monthly behavior." He didn't look the other in the eye at all and notice a small, green hamster enjoying it's self in a bag of cheese puffs.

Mephisto sighed, "I told you before, it's only nature for him to touch him-"

"That's not it!" Yukio stopped it right there. Mephisto was playing with him but he wasn't in the mood. "Please, this is important, sir! I...I want to know if there's anything to...block his hormones..." He felt his face redden a bit but stood his ground. Mephisto grinned wider, "You mean, get him nutered?"

"NO!" Yukio shouted and watched Mephisto giggle and he swore that hamster smirked at him. Yukio was a straight arrowed, goodie two-shoes, and always wanted to be seen as an adult, and when he gets so fustrated, Mephisto can see his brother in him. He did love to toy with Rin, since he gets riled up so easily, but Yukio can be fun too.

"Or perhaps one of those special dipars they put on female dogs to prevent other from smelling her scent? I'm pretty sure Rin is letting out some kind of oder." He watched Yukio's left eye twitch under his glasses. Yukio took a deep breath and sighed, trying to calm down, "Is there any potion, or device to lower a demon's hormones when they go into heat?" Yukio was at the end of his rope right now. He really didn't want to talk to Mephisto about this, but who else could he turned to?

Mephisto scratched his beared chin, "Hmmm, there really isn't. If there were such a thing, I'm pretty sure Mr. Angel will see to it that Rin and I are to under go it." Yukio sighed again, and tossed the controller on a empty bean bag. "I don't think I can live under the same roof with Rin when he gets like this. I'm sick of it. The very thought of him just giving himself away to just anyone makes me sick. I want to punch him! Lock him up somewhere and only I can visit him! I just want to-"

"Have him all to yourself?" Mephisto finished, tilting his head to the side and smirking. A paused passed by and Yukio felt light headed. He clutched his fist until they shooked, he bit his bottom lip, and felt heat up to his neck. "Why?" he whispered mostly to himself, "Why am I feeling this way? I don't want to, it's sick and immoral! I'm suppose to protect him and yet I'm over here...I hate him and I hate myself!"

Yukio left. He didn't expect Mephisto to stop him because the guy didn't care. He was their current caretaker but he didn't care. He wasn't Fujimoto and Yukio didn't expect him to be. He returned home later that evening and stopped at the dinning room door, seeing Rin and Ryuji eating at the table. They weren't in their school uniforms. Rin was dressed down to a white T-shirt and jogging pants and Ryuji was wearing Rin's blue T-shirt with the green alien in the front and some pants that belonged to Rin too. He's hair was a mess, wild and loose, not like his usual style of combing it back. Yukio can smell the faint scent of intercourse from where he was.

He kept going. He hoped they didn't notice him and he ran into his room and shut the door. He jumped on his bed and began to punch his pillow,over and over and over as hot tear flowed down his face. Finally he stopped, tierd but still angry, he took his glasses off and wiped his face with his arm. He flopped down on the pillow and laid there till he fell asleep. Yukio didn't wake up until a faint sound of the bed creaking reaptedly, startled him awake. He shot up and looked around. The room was dark, so it was night. He looked at his clock, 12:15am. He heard a loud moan and Rin panting Ryuji's name. Yukio gapped, he been asleep for several hours and they just went back to doing it again?!

Yukio was finally sick of it. All of it. If Rin didn't want to listen to him and keep acting like a dog, than he has no choice but teach him a lesson!