The power he knows not: ignorance

Albus Dumbledore has prevented Harry from living. Now he's 11 and he won't allow it anymore. Although he's ignorant of the prophecy, it nevertheless guarantees that if Harry starts living, Voldemort must die. In canon everything that can go wrong, does go wrong. In this story things go right. Or: In this reality, Hagrid picked a different line in Gringotts, being helped by a gob...