Maybe Harry Potter could use his magic to solve some of Smallville's strange problems. For example, when there are meteor - related disasters in Smallville, Harry could use spells to protect the town. He might also meet Clark Kent and they could learn from each other. Harry could teach Clark about magic, and Clark could show Harry how to be a hero without relying solely on magic.
Obviously, Harry Potter and Clark Kent would interact a lot. They are both iconic characters in their own universes. Clark, with his superpowers, would be curious about Harry's magic, and Harry would be interested in Clark's abilities. Also, Hermione Granger, if she somehow also ends up in Smallville, would likely interact with Chloe Sullivan. They are both intelligent and inquisitive, so they could bond over solving mysteries or studying the differences between their two worlds.
He might meet the house - elves that have been taking care of Potter Manor for generations. They could show him around the manor and tell him stories about his family.
Obviously, Harry Potter himself. There could also be some Beautox - natives, like a wizard or witch who is an expert in Beautox magic. Maybe Hermione would somehow find a way to follow Harry and she'd be there too, trying to figure out the new magic system.
Well, it might be about Harry Potter entering the world of Beautox. Maybe he goes there by accident, like through a magical portal. And then he has to deal with all the strange things there, like different kinds of beauty potions that are way more extreme than what he's used to in the wizarding world.
Well, he might use his magic to defeat the dragons in Skyrim. Maybe he'd introduce some new spells to the mages there. It could be really interesting to see how his Hogwarts-trained skills fare against the challenges of Skyrim.
One possible plot could be Harry going to America to study at a new wizarding school. He might encounter new magical creatures and spells unique to the American wizarding world. He could also make new friends and enemies there.
He might be amazed by the grandeur of Asgard. Its golden palaces and powerful magic could both intrigue and intimidate him. Maybe he'd meet Thor and they'd exchange stories about their different kinds of magic and heroic deeds.
In this fanfic, perhaps Harry might discover hidden secrets of Potter Manor. He could find old family heirlooms or secret rooms that were unknown to him before.
Well, Harry could be really confused at first. Ouran is a very different world from Hogwarts. He might be shocked by the opulence of Ouran Academy and the strange club system there. Maybe he'd try to find a way to fit in while still being true to his wizard self.