Rin x Reader/Your Guardian Angel

Black Bird

"So the two of you are a couple now?" Bon asked before class was about to start. 

"Yup we confessed at the summer festival." You smiled while you held Rins hand.

"Ohhh so you confessed after Rin punched that guy for you, how romantic~" Shima said.

"Yup, his nose was broken and his parents wanted to sue Rin but when I told them what their son did they apologized." You smiled.

"Everyone get to your seats, class is starting!" Yukio said as he walked into the classroom.
The lesson was very boring and you almost slept in, until you heard that in a few days all of you would visit a special force of the true cross order. You shot up when you heard the name of your special force being mentioned.
"Oh God no..." you mumbked silently.

Days passed and Rin didnt really have much time for you because he had to train how to controll his flames. But you also were quite busy, you were attending a lot missions lately that started to drain the life out of you. And when you heard that a demon had broken into campus somehow and attacked students you weren't looking forward to the mission at all.

"Ahhhh my favorite angel! (Y/N)!" Mephisto greeted you.

"Mephisto!" You acted like you were happy to see him.

"Oh and I see for once you are wearing your uniform!" He said pointing to your excorcist uniform that you rarely wore.
It took you a lot of self controll to not just snap at him.

"Yup, thought it was appropriate." You smiled weakly.

"Follow me!" Mephisto said and lead you to the room the demon was in, which was surprising your cram school classroom.

"Ughhh!" You covered from your nose. The whole room smelled like demon which was a very unpleasant smell to you.
"It reeks of demon in here." You mumbled as you picked up a black feather off the ground.

"I need to speak to the students that saw the demon, and to anyone that might know whats going on." You said.
"Where are all the exwires at the moment?"

"They are checking if all of the magic circles are still intact." Mephisto answered.

"Ok, I would like to speak to all of them. Who fought the demon?"

"Rin Okumura and Izumo Kamiki."

"Are they hurt?!" You asked worried and Mephisto shook his head, which made you sigh in relief.

"Ok let's get to work then!"

After speaking to Izumo you didnt really knew more than before. She just told you that Rin and her got attacked by the demon in the hallway and that it looked like a big black bird. 
But after you spoke to Bon and Shima, that were very surprised to see you in your uniform, you could gather some more information and maybe even solve the puzzle.

"I think I know how the demon got in here. The magic circles of the school are all intact so someone must have let the demon in, and I think I know who and why." You explained to Mephisto.

"Go on, enlighten me." He smirked and you knew that he was a bit impressed. 

"Bon and Shima told me that the only weird thing that they have been witnessing is that Konekomaru is nowhere to be seen. He doesn't answer their text and wasnt in school. I know as a fact that he isn't really strong and he knows. I think a demon offered to make him stronger, and by taking the offer he let the demon into the school without knowing." You explained and Mephistos started clapping.

"You never fail to amaze me (Y/N)! They call you demon hunter for a reason. " he smiled.

"You know I hate that name...Im just a normal excorcist and nothing special."