Who Are You?

Y/N L/N is a powerful mage who is not known throughout Fiore. She is as powerful as the dark mage, Zeref. As she joins Fairytail, she decides to not use her magic for she can kill them all. She becomes really great friends with Natsu Dragneel. They are the same age but somehow, Y/N gets into fights with Erza Scarlet. As they grow, the girl gets more interested in the dark mage. What will happen if she meets face to face with the dark mage himself? How will her best friend, Natsu, react?