Dark as Night

After Lily's death, her elder son was sent to live with the Dursleys. Abused for six years, Harry was rescued and adopted by Voldemort. He grows into his powers as the Dark Lord's heir at Durmstrang and, eventually, Hogwarts. Before the end, Harry has to face his biological family once more as the heir to the Dark Lord. Dark!Harry (adopted)Father!Voldemort