A/N: This is my first fanfiction ever! Although, yes, I've read many fanfics. (Look at how many favorites I have!) Anyway, I hope you enjoy! If you don't, oh well, I was just trying to satisfy a plot bunny. I'm more of a reader and a critic than a writer tbh ^.^

Disclaimer: I do not own Blue Exorcist/青の祓魔師 or any of its characters.

The first time he saw the book, it was on Yukio's desk in a pile of homework books. It was a dull shade of red, about the same size as Yukio's other textbooks. His brother was out on a mission, as usual. Rin barely spared the book a glance, much less remembered it being there. He wasn't interested in any of Yukio's homework. It gave him too much of a headache. To think his brother did even more advanced schoolwork than him always dumbfounded him. His schoolwork was hard enough, but Yukio's was even more challenging.

Rin was impressed and proud of his brother's intellect. The smart twin was capable of doing so many things. He was the model overachieving student, not to mention almost on par with a responsible adult. Sometimes the cram students forgot that Yukio was their age due to his superior status, clean look, and self-control. Rin wasn't jealous of his brother, although he sometimes wished he was a bit smarter, so his life wasn't always so difficult.

The next time Rin saw the book, Yukio was poring over it late at night. He could barely see the pages of the book underneath Yukio's hunched over figure. He figured Yukio was studying for a difficult test. He only looked so focused when it involved something complex and challenging. It made Rin's head hurt thinking of what could be so strenuous for Yukio. His brother ended up sleeping two hours that night. (1)

Such repeated for many days. Not only did it occur at night, but at all times of the day. It seemed Rin could never see Yukio without his nose stuck in the book. During mealtimes, at breaks, on his teacher's desk at cram school, and even while he slept! Or, at least Rin could swear Yukio slept with the book. He only saw it happen once when he woke up in the middle of the night to use the restroom. One of those rare times he was awake while Yukio slept.

Yukio began to look like a zombie gone back to life. Dark circles rimmed his eyes and he yawned about 5 times a minute. More recently, he began waking up late. His uniform was wrinkled, his hair uncombed, and his glasses askew. Once or twice he forgot his tie. The other cram students thought Yukio almost looked like Rin with his messy look. Rin didn't know whether to feel offended or not.

But such behavior was unusual for Yukio. Rin scrambled for an explanation. It wasn't time for any major tests, like midterms or finals. They had only begun the semester! He didn't know what could cause Yukio to be stressed and stay up late at night. Wait, scratch that. Yukio had a lot to worry about. Namely, Rin himself. But that didn't explain the strange obsession with the book! Rin resolved to find out, or at least send Yukio to bed earlier. As the older brother, he was allowed to do that. Not to mention all that studying was probably rotting out Yukio's brain. (At least, Rin thought so. Bon begged to differ.)

That night, Rin decided to confront Yukio during dinner. He was going to make Yukio's favorite, sashimi. (2) It would make Yukio open up easier if he was comfortable. And he could always threaten not to give Yukio any food if he refused to tell. Plus, Yukio wouldn't take it kindly if Rin demanded answers while he was busy doing homework or something important. Particularly with the book around.

Rin finished the last piece of sashimi, before calling Yukio for dinner from the kitchen doorway. He waited for a couple of seconds, before frowning. He couldn't hear any approaching footsteps. Unusual. Yukio typically came for dinner right away. His brother wouldn't admit it, but he was generally as hungry as Rin when mealtimes came around. He waited another minute before leaving the kitchen. He stalked up to the room he shared with Yukio, and slammed the door open, loud enough to wake the dead. He might have dented the wall or broken a couple hinges on the door. To his surprise, Yukio was sleeping on his desk over the book.

Rin's scowl grew deeper. Yukio's unhealthy obsession with the book made him completely pass out from exhaustion. If Yukio couldn't even wake up after he slammed the door open, he doubted anything else would. On the bright side, at least Yukio could catch up on some sleep. At this, Rin's face softened. He gently lifted Yukio from his chair and laid him on his bed. He removed his brother's gear and was about to place it on his desk when he noticed the book.

It was worn and old. The pages were yellow and wrinkled. It was a pretty thick book by Rin's standards. Rin decided to take a peek at the page open. He was curious as to what was causing his brother a lack of sleep. The amount of headache one sentence would give him would help him know the amount of stress his brother was going through, and maybe he could demand that the school give Yukio less advanced stuff. Meaning, he would threaten Mephisto with the tip of his blade and his flames.

Rin dropped his brother's gear on the floor before picking up the book. One glance, and Rin was flying through the book. Unconsciously, Rin was verbalizing the words as he read. Before he realized the oddity of him reading fluently, he heard a click behind him. Eyes wide open and still holding the book, he turned around. Before him, Yukio (when did he get up?) unsteadily held a gun. His face was a strange mixture of astonishment, fear, and anger. Rin jumped and dropped the book in fright.

He pointed a finger at Yukio. "What the hell, Yukio? Don't point a gun at me! And when did you get up?"

"I should be asking you what in the world were you doing. I wake up hearing murmuring in a strange language, not to mention all my gear was gone. And when I figure out it's you, I'm thinking you were possessed or had lost control!" said Yukio.

Rin's brow furrowed "Eh? Me? I was just reading this book." He points to the red book on the floor.

There was a slight pause while the brothers took a moment to process the words.

Yukio gaped at his brother. He exclaimed, "You were reading? As in, an actual book? Wait, scratch that. You were reading that? I'm struggling to read several pages an hour!"

Rin picked up the book. "Wait, what? This book's a piece of cake. I bet a ten year old can read this in a couple of hours."

Still gaping, Yukio stammered before saying, "Nii-san, that's written in Enochian! Also known as the common demon language. I'm trying to read it so I can familiarize myself with the writing. At most I was hoping to learn the language, but," he lowered his head in shame, "I'm having a great difficulty just reading it."

Rin stared at Yukio. It was strangely exhilarating accomplishing something his brother couldn't. He was having difficulty in something academic, while Rin was breezing through it? Not to mention it was his first time at Enochian? And- wait a second, he could apparently understand Enochian? And read it aloud?

"Whoa, whoa, wait a second, if this is in Eno-whatever and not Japanese, then how the hell can I read it? I've never even seen this language before!" he exclaimed.

Yukio thought for a moment before providing the brilliant answer, "Maybe it's because you're the son of Satan, the god of all demons? We don't really know when or by whom Enochian was invented, but maybe it was Satan?"

He paused before adding, "Maybe that's also why you're so illiterate. Or at least in Japanese. You're probably meant to read Enochian, not anything else."

Rin didn't really know what illiterate meant, but he figured it wasn't something great. He scowled. "Hey, what's that supposed to mean? Take it back, I'm so not, ill-whatever. I'm not sick, at least!" (3)

Yukio flashed a rare smile. "Illiterate means not able to read, Nii-san. Goodness, you also need to touch up on your vocabulary."

Rin glared at him. Then a strange thought crossed his mind. He shrugged. "Well, at least I can understand two languages. Particularly one rare. I guess that can be handy. But still, you didn't explain why you were reading a demon's guide to flirting."

Yukio flailed around in denial while screeching, "Damn Mephisto!" Meanwhile, outside their window, the devious Mephisto Pheles cackled from his levitating chair. He was, after all, the one who provided the book.

(1)- Apparently Yukio sleeps 4 hours on average! So I had to give him something that would really exhaust him. Talk about overachieving and over-stressed!

(2)- It's true! I looked it up!

(3)- I know it's Japanese, but I couldn't help but make that joke! xD

I hope you enjoyed this! Please feel free to criticize on any mistakes I made. I absolutely despise mistakes, so I'll try to fix them up ASAP! I also hate when characters are OOC, so please let me know and I'll try to take the time to fix it. Most importantly, thank you for taking the time to read. If anyone wants to see anymore, ask? Idk, maybe I'll write more if I get an inspiration. Tbh, this is more of a practice for me. Just a small plot bunny.

10/15/15 Edit: Thank you SuperiorDimwit! I looked it over and made many major edits. I hope it's better.

10/16/15 Edit: Thank you chibi tantei and again SuperiorDimwit for more advice! I made a couple other edits, minor compared to yesterday. I tried to make it smoother. Can't do much about the beginning. I don't think I'll do anymore edits besides grammar, or else I think I'll get sick of this story! xD