Another possibility is a scenario where Voldemort decides to expand his reach into the non - magical world and Batman becomes aware of this threat. He would then enter Hogwarts undercover to learn about magic and form an alliance with the Order of the Phoenix. The contrast between Batman's brooding, non - magical detective nature and the magical world would make for an interesting story.
Perhaps there could be a situation where some of Batman's rogues gallery, like the Joker, get their hands on magic items from the Harry Potter universe. Batman, with no knowledge of magic at first, has to rely on Hermione's intelligence and Ron's loyalty as they try to stop the chaos the rogues are causing in Gotham and the wizarding world.
One idea could be that Tinkerbell finds her way into the wizarding world of Harry Potter. Maybe she gets accidentally transported there by some magical mishap. She could use her fairy magic in Hogwarts, like helping to repair broken objects in a more sparkly and unique way compared to the Reparo charm.
One idea could be that the Avengers are somehow transported to the wizarding world. They might be initially confused by the magic but then start to work with the Hogwarts students and teachers to fight a common enemy, like a dark wizard who has also harnessed some sort of Muggle - like technology to become even more powerful. For example, Voldemort could team up with Hydra remnants to create a super - weapon that threatens both the magical and non - magical worlds.
A fun concept could be a Transylvanian wizard coming to Hogwarts as an exchange student. This wizard has a pet dragon that is different from the ones in the UK. He brings with him knowledge of Transylvanian magic, like how to use the power of the full moon in a different way than British wizards do, which intrigues Harry and his friends.
One idea could be that the characters from Riverdale somehow find themselves in the wizarding world of Harry Potter. Maybe Jughead could be a Muggle - born wizard who discovers his powers while at Hogwarts. He might write about his strange new experiences in his journal, just like he does in Riverdale.
One idea could be that Loki, being the mischievous character he is, finds his way into the wizarding world of Harry Potter. He could start causing chaos in Hogwarts, perhaps by disguising himself as a student or a professor and playing pranks that are far more elaborate than those of the Weasley twins. For example, he might turn the entire Great Hall into an ice rink during breakfast time.
One idea could be that the Hulk somehow gets transported to the wizarding world. Maybe a magical experiment gone wrong by a Hogwarts student creates a portal. The Hulk's brute strength would be a shock to the wizards and witches. He could end up causing chaos in Hogwarts, knocking down walls and scaring students. Wizards would try to use spells on him, but his strength might make him resistant at first.
One idea could be that Lucifer somehow ends up in the wizarding world. Maybe he's intrigued by the magic there and decides to play some tricks on the Hogwarts students. He could start by disguising himself as a new dark arts teacher, causing chaos in the classrooms.
One idea could be that Killmonger somehow finds his way into the wizarding world of Harry Potter. Maybe he stumbles upon a magical portal while on one of his missions. He could then use his combat skills and strategic mind to navigate the complex politics of the wizarding world, perhaps forming an unlikely alliance with Harry Potter to fight against a common dark magic threat.
One idea could be that Hogwarts is transported to the Jurassic Park island. The students and professors have to use magic to survive against the dinosaurs. For example, Hermione could use spells to create barriers to keep the T - Rex at bay while the other students try to find a way to get back to their normal location.
Another idea is that the Death Eaters in Harry Potter create a new kind of maze similar to the one in the Maze Runner as a form of torture or experiment. Harry and his friends then team up with the Gladers to escape this new, magical maze.