Seven Months Gone, Three Years Missing

For seven months, Lucy is ignored. She leaves for three years after a reluctant Natsu and more willing Team kick her off. She comes back powerful and changed, haunted by a dark past. When her past shows up one day threatening her family, who does she turn to? How will she save Erza from the same fate she suffered? May be bumped up later to M for violence and relationships. NaLu.