Stuck in Blue Exorcist {Blue Exorcist fan fic}

Natsuki Kusaka is your everyday 15 year old girl. Well, other than her cloth choice(Jeans, T-shirts, and not one skirt/dress in sight), and multiple fist-fights... Yeah, so other than that you could say she's pretty normal! :) But, in every story, the main character has a background; and it's almost always a tragic one. Sadly enough, this is true in Natsuki's case.. Her 'parents' treated her like a lifeless rag doll, a cutting board, etc. And she has the scars to prove it, no matter how much they Deny it. But, she doesn't have deal with that anymore! Yes, I'm serious. And No, she's not dead. Natsuki actually lives with her cousin, who might as well be her older brother. Now, all things is peaches and creame. Right? weeell... I mean, it is... until she heads out to find her real parents. Yep. She's adopted. Taking a meaningless walk with no destination, and no way to find her parents, her life changes as she finds herself brought into a world of demons and Exorcists. A world where Satan had children who wanted to kill him. A world... where her parents were from?