Nalu: The Lone Slayer

To say she hates her father would be an understatement. She wished he was dead. Lucy was raised in a loving home with two amazing adopted parents, but that didn't stop Jude from coming to take her from them. Lucy Heartfilia didn't even remember her birth father, and after the day he left her in the woods to die as an infant, she didn't want to. Then, one day, he came looking for her. He made her believe he had killed the only mother she had ever known, and then, took her, but only to use her as a power source. One day, she decided she has had enough.

Natsu Dragneel is a well known and respected mage of Fairy Tail, even if it is as Salamander and not Natsu. One day, while looking for his adoptive father, Igneel, in Crocus, he runs into a beautiful girl his age who claims to be a Celestial Wizard. He takes her back to his guild where she is welcomed as part of the family. Little do they know, she isn't even using a fraction of her true strength and she will bring them on many journeys to come.

Nothing but the story line belongs to me. Everything else, credit goes to the rightful owners.
Original story idea came from @Otaku-Chibi