HP: Defense Against the Dark Arts Professor

A time traveler who knows all the plots of "Harry Potter" grew up in the same orphanage as Tom Riddle. With the superiority complex of a "prophet", he tried to lead the future Dark Lord to the light. However, all his efforts were in vain when he discovered that Tom was secretly making Horcruxes - a fierce quarrel, a complete break, until he was forced to destroy his best friend's body with his own hands. Failure and self-blame pushed him back to Hogwarts and became the cursed Defense Against the Dark Arts professor. During Harry's seven years in school, he was an outsider and the driving force behind the scenes: secretly guiding the Iron Triangle to resolve the crisis, watching the inertia of fate with a cold eye, but stepping forward at the critical moment. However, his biggest secret is not his identity as a time traveler, but when he collided with Voldemort's spell on Halloween night, a fragment of his own soul was quietly injected into Harry's body... This is a story about how a "prophet" was ridiculed by fate, and how he accomplished self-salvation in the confrontation with doomed tragedy. When the ending of the story has already been written, should you obey or resist? Perhaps the real magic lies not in changing the past, but in how to face irreversible failure.