One idea could be a crossover where Hikaru Hitachiin, with his mischievous nature, gets sorted into Gryffindor. He then teams up with Harry Potter and uses his unique pranking skills to outwit the Slytherins. For example, he could use his twin - like antics to create distractions during Quidditch matches against Slytherin, just like he does in the Ouran High School Host Club to mess with the other club members.
Hikaru is very observant, which could be useful in the wizarding world. He might notice small details about the magic around Hogwarts that Harry has overlooked. In return, Harry could teach Hikaru more about the serious aspects of magic, like defense against the dark arts. Their interactions would be a mix of cultural exchange, with Hikaru sharing his Japanese school experiences and Harry introducing the wizarding world traditions, and also a combination of their different personalities clashing and then meshing together as they face various challenges at Hogwarts.
One idea could be a crossover where Luffy and his crew end up in the wizarding world. Maybe they're searching for a magical treasure that's said to grant any wish, and they team up with Harry Potter and his friends to find it. They could use their Devil Fruit powers and wizardry together in battles against dark wizards who also want the treasure.
Gabriel could be an exchange student from a far - flung wizarding school. He brings with him a different style of magic. Harry Potter is both curious and cautious about him. As they study together, they find out that a series of strange magical occurrences around Hogwarts are related to a curse from Gabriel's home school. Together, they try to break the curse while also learning about the cultural differences in magic, which enriches their own magical understanding.
Another plot idea is that some of the characters from Harry Potter, like Hermione, are transported to Narnia. There, they meet Aslan and learn about his world. Meanwhile, Aslan could send some of his Narnian creatures to the wizarding world to help Harry and his friends in their fight against the dark forces. This exchange of cultures and magics could create a really engaging story.
One idea could be to combine the magical elements of Harry Potter with the survival aspect of Hunger Games. For example, wizards and witches from Hogwarts are forced to participate in a Hunger Games - like competition in a magical arena. They can use spells for survival and combat.
One idea could be that Peter Parker gets magically transported to the wizarding world. He could use his Spidey - sense to detect dark magic or danger in Hogwarts. Maybe he teams up with Harry Potter to stop a new villain who is using both magic and advanced technology to cause chaos.
One idea could be a crossover where Harry Potter and Ciel Phantomhive meet in a magical realm that combines the wizarding world and the Victorian era of Black Butler. Maybe Harry is on a mission to find a dark magic item that has somehow ended up in Ciel's world, and they have to work together despite their very different personalities and upbringings.
One idea could be that the main character from Reborn is reborn into the Harry Potter world as a wizard with his unique skills. He could use his combat abilities from Reborn to face the dark wizards in the wizarding world. Another could be that a character from Harry Potter gets reborn in the Reborn universe and has to adapt to the different rules and powers there.
One interesting idea could be a fanfic that focuses on the Marauders' time at Hogwarts. It could explore their pranks, friendships, and how they came to be the legends that we hear about in the original books. For example, showing how they created the Marauder's Map in more detail.
One interesting idea could be a fanfic where the Marauders attend Hogwarts during modern times. They'd have to deal with things like smartphones and social media while still maintaining their mischievous ways. Another could be a story that focuses on the lives of the house - elves after the events of the books, perhaps exploring their newfound freedom. And a third idea could be a fanfic about a new dark wizard emerging in the wizarding world years after Voldemort's defeat, and how the new generation of Hogwarts students respond.