The Other Demon.

New Student.

"Isoya, what do you think you're doing at my school?" Mephisto asked the demon that was perched atop the fence of the roof. "I... wanted to enroll. As an exorcist." Isoya muttered, twirling a scythe in his left hand. "Why now? You've been more than adamant about not 'picking sides' as you put it."

"You know damn well why." Isoya muttered. Mephisto smirked. "It must because of Rin, right?" Isoya remained silent for a moment before he sighed, "You know I don't like this, right?" Mephisto nodded, all traces of a smirk gone. "Yes, I am well aware of your situation. After all, it's rare for a demon to have any kind of match." Isoya muttered a curse before he stood up and asked, "Am I able to?" Mephisto nodded, "Yes, I think that you will be a nice boost for Rin. After all, his friends are abandoning him right now."

"They're WHAT?!" Isoya yelled.
"Calm yourself, it's out of fear more than hatred. They all hate his father, this is true, but they also fear that he will become his father. Just as the Vatican and Knights do." Isoya sighed again. "...When do I start?"
"Tomorrow."
"Fine."

~~~~~~~~~~~~~~

"Everyone, there's a new student joining you. Yes, we know it's late in the year, but he shows potential." Ms.Shura said. "Come on in." She said. Isoya walked into the classroom to see that everyone was either to the far left and back or far right and back of Rin. He huffed and sat next to Rin. "Hey," He said, "name's Isoya Yoshihiko. Nice to meet ya."
"Rin Okumura." Rin said, giving a small smile. "I've heard about you, Prince of darkness." Isoya said, smiling at him.

"Thanks for the reminder." Rin muttered. Isoya was silent for a second. "Sorry, that wasn't my intention." He said softly. "I was just, um, trying to lighten the mood in here." Isoya said softly. Rin gave Isoya a crooked smile, "It's okay." He said. Isoya's tail wriggled out of the hiding place and started wagging.

"Holy shit! He has a tail just like Okumura!" One of the guys said.
"Shit. Guess the cat's out of the bag." Isoya said, smiling wide at the person who said it. "Are you another one of Satan's spawn?" The rooster haired guy said. Isoya chuckled. "Hell no. It wouldn't do for a demon's match to be their brother."
"Match?" The kid with glasses said.

"Think of it like a soul mate for demons. Either demon can reject the other, but their match will always trail behind them. Watching and waiting for the other to be happy. Once that is achieved, the match will simply... Fade back to gehenna. Forever. They will not be allowed to meet again." Isoya said, a hard look in his eyes.

"So you're a match for Rin?" The blonde girl asked. "Yeah. I was hoping to wait and get to know him before I said anything about this, but it seems as though that is not going to be the case."

"Sit down and shut up." Ms.Shura said. We are aware of him being a demon like Rin. However, he has a similar reason for training to be like you. Satan has taken his family from him as well." Ms.Shura said.

"How?" Rin asked. "Uh, if you don't mind, anyway."
"It's fine. 15 and 1/2 years ago, I was born. Since I had demon blood, Satan tried to turn me into a vessel. The blue flames erupted from my mouth. Everyone in the house was burned to ash and Satan realized that I would not be suitable. He left right before my mother got home. She knew if she took me to a temple I would be killed.

"She sent me to Father Fujimoto, but he couldn't take me in. He knew Rin was going to be born soon. He knew what he would have to do if he accepted me. He sent me to a friend of his who raised me as a human for the most part. A friend of his that is, for the most part, in love with our world." Isoya said softly.

"I'm so sorry for what happened to your family." Rin said.
"Oh, no. It's not your fault. After all, you are not your father. Just as I am not mine." Isoya said, putting a hand on Rin's shoulder. "What demon are you the son of anyway?" Rooster head asked again. "Ah, the demon Furfur. A compulsive liar. He can create love between a man and a woman, create storms, tempests, thunder, lightning, and blasts, and teaches secret and divine things." Isoya said.

"Wow. He does a lot. Are your powers sealed like mine?"
"Kind of. I did it myself, after all, I kept sparking when I got pissed off. I stored most of my energy and power in this." Isoya pulled out his sythe. "I like the look of the sythe more than a sword. It's kind of fitting. Like an angel of death itself, we strike demons down and send them back." Isoya said, twirling his sythe carefully.

"Speaking of striking demons down, let's see what you can do, shall we?" Ms.Shura said, tossing a vial of demon blood to Isoya, who caught it easily. "Sure. Lets find a place I can demonstrate, shall we?" Isoya smiled. Ms.Shura used a key to open up an empty, unused room. Isoya opened the vial and dropped some on the floor. A giant, low level demon rose up from the floor and stared at Isoya. "Come on, big and ugly. Let's see what you can do." Isoya smirked.

~~~after most of the fight~~~

Isoya sliced the demon in half. Dark, almost black, purple lightning shot through the demon and electrified it to death, back to Gehenna. Isoya landed lightly on his feet, his tail swishing back and forth. The room was a bit of a mess, but otherwise was okay. Isoya grinned and turned to Rin. "I can help you with your powers if you'd like." Rin was slightly flushed as he agreed.

(So, I know I said I'm not gonna make another story, but I recently watched Blue Exorcist. Every episode in one day, and uh, I decided to make a story. It's Rin x my OC. If you wanna, you can pretend you are my OC? I guess.)