Affliction (Harry Potter fanfic)

Serenity Lily Potter is Harry's twin. She grew up with a father and a brother. Their mother had passed and their father blamed her. She was brought up in misery and pain, mentally. She lost all of her friends but one because of her father, only to find out that her father isn't her father. At age 14, Serenity goes to Hogwarts to find a future she never imagined.