There's only one world, reality, the rough and hard reality. But when you're reading, watching a movie or something else, then it seems as if the world the characters live in is also real. Maybe it is, maybe not, who knows?
When the final battle of hogwarts is over, too many people were lost. So the Emerald Trio (aka golden trio) and their friends decided to travel to the past to change the course of the future.
Hogwarts Legacy Crossover
(Does NOT follow movies. New stroyline. Some dates may differ.)
*I do NOT own Harry Potter or J.K Rowling's characters*