My Adoptive Sister (GrayZa Fanfiction)

Gray has a new adoptive sister. and he really hate her so much. . but, what is this growing feelings inside him? why he feel lonely when she's not around? why does its feel hurt when seeing her with another guys? haha who knowss?? XD (GrayZa with a slight NatZa) disclaimer : I don't own fairy tail. if i own fairy tail...