Separated at Birth

(Based on my challenge, "Harry Tohsaka") Risei Tohsaka, Rin's twin brother, was abducted from the Tohsakas as a baby to another world and blood adopted into the Potter family. Now, after defeating Voldemort, a weary Harry Potter travels back to the world of his birth, and works to reunite his family. But between Magi politics and the upcoming Holy Grail War, it's going to be tough.