Hello all! I haven't written anything in a long time. This is my first attempt at a Ao no Exorcist/Blue Exorcist story. I'm still working things out, but this is the first chapter, likely the most boring, bare with me, it's mostly just introductory. This will take place two months after the ending of season 1 (yes I'm aware it isn't canon). Feedback is certainly welcomed and encouraged!

I don't own any characters or Blue Exorcist. I only own the OC's created in the story.

This would be the first time she's ever been outside of Rome. While she was excited for the change in scenery, Calista wasn't here to sight see. No, she'd been given a mission to keep a close eye on a pair of demons working as exorcists inside the True Cross Order. Rin Okumura and his twin brother Yukio. Both were considered dangerous and unpredictable. Why she'd been chosen for this mission she didn't understand. Maybe it was because she was their age and half demon herself? Regardless, she had a job to do and she would see it through. If she found that either boys were a threat, she was to eliminate them immediately. Even though they already had more than one exorcist watching over them, they were now considered to be too close to the boys to perform their duties, should they need to be killed.

So they sent her with strict orders not to reveal herself to them.

She stood outside of True Cross Academy, starring up at the enormous school and wondered how anyone could possibly navigate their way around such a place. Was all of this really necessary? It seemed a little excessive to her.

"Seems like someone is compensating for something to me." Rolling her eyes, Calista readjusted the shoulder strap of her backpack. "Can't believe I have to attend school here and go through cram school all over again." Shaking her head as she spoke to herself, Calista made her way towards the huge school where she would get her classes and dorm room. First she needed to see Mephisto, the principal of this school and the only one who was to know of her involvement here.

It took her over an hour to find his office...having to ask more than once for directions. When she finally comes to her destination, she wasn't in the greatest of moods. Without bothering to knock, she enters the room, her aquamarine eyes blazing with annoyance. "Could you have made this place anymore confusing?!"

He looked up at her with his green eyes, just as annoyed by her barging in as she was by how confusing his school was. "My girl, it is rude to enter before knocking. Didn't they teach you any manners in Rome?"

"Oh shut it," She dropped her backpack on the ground beside a chair, before sitting down, crossing her legs. "You know why I'm here, and you know you're not to speak a word of my presence to anyone."

He waves a hand dismissively, passing a square piece of cheese to a little green hamster. "Yes, yes, of course. The Okumura brothers have no idea you're coming or your involvement with the Order. The only one who knows you're coming is Yukio, who is expecting a new student this afternoon. As I do not have any open rooms in the girls dorm, you will have your own separate room in the Okumura's building. I hope that will suffice?"

"Yeah, that'll be fine. This way I can keep a better eye on them without appearing suspicious." She stands back up, lifting her bag as she does. "As you well know, the Vatican doesn't trust you or them. That's why they sent me."

Mephisto held out a key that would allow her to access the cram school. "Of course, my dear, but I do wonder..."

"What's that?" She glanced back at him over her shoulder after taking the key and turning back towards the door.

"If they truly trust you, as you seem to think they do. Especially since you're no ordinary demon.~"

Calista didn't bother to answer him, instead her eyes narrowed into a glare.

She found the dorm building fairly easy. Then again it was the only building on the whole property that looked like it should be completely abandoned. The fact that it wasn't, was mind boggling. "You're kidding me? Students actually live in this dump? The whole place should be condemned!"

"Where do you get off on calling our building a dump?" The irritated voice behind her, announced the presence of another.

Turning around, Calista came face to face with who she suspected to be one half of the Okumura brothers. The one in front of her had dark blue/black hair and blue eyes. What stood out though, was the pointed demon ears, long black demon tail, and pointed fangs which were currently bared at her.

Before she addressed him, she had to remember to keep her cool and not give herself away. "Sorry," she apologized, giving him a small smile. "I didn't mean to offend you. I'm new here and just didn't expect to be placed in this dorm building."

He glared at her a moment more, as if he were trying to get a read on her. "My brother and I are suppose to be the only ones in this building."

She nods her head. "Yes, I was told that there weren't any empty dorms available in the girls building, so the principal placed me here until further notice." Remembering the custom in Japan was to bow when greeting someone, Calista quickly does so, so as not to further offend him. "My name is Calista and I just transferred here from Rome. I'm to start the cram school today as well."

His eyes seemed to widen a bit as she mentioned this. "So you're going to be an Exorcist too?" He smiled and uses his thumb to point at himself. "I'm Rin Okumura and I'm an Exorcist too!"

So this was the older brother then? She heard about him. Unlike his younger brother, Rin had been born with Satan's blue flames and struggled to control them, having already lost himself once before. This was the one that needed watching over the most.

"It's a pleasure to meet you, Rin." She looked down at her watch on her left wrist, checking the time. "Hey, do you think you could help me get to the cram class? I was given this key, but I'm afraid I'm terrible at directions." Which wasn't a lie, like earlier, she was easily lost. Especially in new places.

"Yeah! Sure! No problem. I was just on my way there now in fact." He walks to the door of the building, slipping the key into the lock and turning it. When he opened the door, it led into a hallway that didn't look like it belonged inside the building the door was attached to. "My little bro Yukio is our teacher."

"Mr. Okumura is expecting me, though I haven't had the pleasure of meeting him yet." As Rin enter the hallway, Calista followed behind him.

"He's alright, I guess. A bit of a know-it-all." Rin shrugged his shoulders, leading the way.

"I've heard he's a genius. One of the few to become an Exorcist at such a young age. A prodigy, so to say."

"Yeah, I guess so." He seemed a bit annoyed by this, placing his hands behind his head. "But he's not all that. I'll catch up to him before he even realizes it."

She felt his presence before she heard speak up behind them. "You have a long way to go before you catch up to me."

Both Calista and Rin paused in their tracks, turning around to face the one who'd spoken. As Calista looked at the boy behind her, using his finger to push his glasses back up, she instantly knew that this was the other brother; Yukio Okumura. His eyes were a deeper shade of teal than hers. Paler than his older brother, but taller and more mature looking. Beneath his left eye were two moles, and one under the right side of his lips. A pair of pointed demon ears poked out from beneath his dark brown hair and she could only assume that his tail was carefully tucked away under his True Cross Order uniform; unlike his brother who left it exposed. There was no denying that there were major differences between these twins. She could tell that in just the few minutes of being around them.

"Yeah, well, you heard me. I will catch up to you sooner than you think!" Rin stated confidently.

Though he went unnoticed, Yukio's attention on her. Earlier, Rin had watched her closely, but seemed to quickly dismiss her, whereas Yukio's eyes seemed to try and see right down to her soul. It was a bit unnerving, but she wouldn't let it break her resolve.

"You're the new student then, from the Rome district." He said it matter-of-factly, like a true instructor.

Calista nods and like with Rin, she bowed to him. "That's right. I'm Calista, recently transferred here. It's a pleasure to meet you, Mr. Okumura, I look forward to learning under you."

Yukio watched her a moment longer. She could tell he was suspicious of her. Which he had every right to be. She'd be suspicious too. "Very well, you're both late, so let's get in and get started." He pushed his glasses once more as he moved between her and Rin and into the class room.

Calista stood there for a second, Rin going on ahead of her and following his brother into the classroom, grumbling. So those were the Okumura Brother's. Rin would be easy enough to keep her cover around, but Yukio….well he would be a bit more challenging. She smirks to herself, and as she did, a pair of sharp canine fangs glinted in the low light, the thought of a challenge exciting to her. It had been a long time since anyone or anything had made her this excited.

Hiding her fangs, she too followed the twins into the classroom; eager to see how this mission would turn out.