An older Harry defeats Voldemort, but soon realizes the world he saved is not for him. Maybe if he started on the path he took sooner, things might've ended differently. He intends to find out. Time travel, but not the kind I've read before.
We all know how Harry turned out living with his relatives, and we've all read about Harry being raised by Sirius, Dumbledore, or the unknown, but powerful mentor. What if this mentor was Pai Mei?