You find out your roomate is a vampire in a disturbing way... how do you solve this?(yes, i know something is wrong with the story, sorry.)

Find out. how Lucy and her friends leave fairytail

How would you feel if your own friends turned against you? How would you react? That's what Lucy's situation was. Kicked out of The FairyTail guild with unending showings of rejection, Lucy was forced to retreat and train as hard as ever. Leaving the city of Fiore and setting foot in another world, she was determined to destroy them in the upcoming Grand Magic Games. Her one goal, was to be the strongest of them all....

Yandere (ヤンデレ) is a Japanese term for a person who is initially very loving and gentle to someone (or at least innocent) before their devotion becomes destructive in nature, often through violence and/or brutality.