A Harry Potter and Star Wars crossover would be really interesting. Picture Harry and his friends traveling through space in the Millennium Falcon, learning about the Force and using their magic in combination with Jedi skills to fight against a new dark threat that combines the power - hungry Sith and the dark wizards from the Potterverse.
Some unique ideas could be that baby Harry has a special bond with magical creatures from a very young age. For instance, he might be able to communicate with Hedwig even as a baby, through some kind of magical telepathy. This could set up a whole different dynamic in the story.
One idea could be a character who uses Dirty Harry - like tactics to deal with the Death Eaters. For instance, being extremely direct and fearless in the face of danger, much like Dirty Harry in his movies.
In some 'Harry Potter Harem' fanfictions, a unique idea is to have the 'harem' members be those who have been wronged by the dark side in different ways. They bond with Harry as they all strive for justice and a better wizarding world. For instance, a character whose family was destroyed by Death Eaters joins Harry's group. This creates a deep emotional connection among the group members and a strong motivation for their actions. It also gives a new perspective on the fight against evil in the Harry Potter universe, as they work together not just for Harry's sake but for their own and the world's.
Well, in some fanfictions, Loki might be interested in the Time - Turner device from the Harry Potter universe. He could try to use it for his own purposes, like going back in time to change certain events in the wizarding world to his advantage. Or perhaps Loki and Harry Potter get into a magical duel where Loki uses his Asgardian magic and Harry uses his wizarding spells. The contrast between their different forms of magic would be really interesting to explore in a fanfiction.
A unique idea could be that a Transformer is enchanted by a wizard to be able to use magic. So it becomes a sort of magical - mechanical hybrid. It could use spells like the wizards and also transform into different forms. For example, it could transform into a broom - like form to fly around Hogwarts.
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.