For a Harry Potter OC Crossover Fanfiction, you could do an OC crossover with the Avatar: The Last Airbender world. The OC could try to understand the concept of bending elements and see how it differs from spell - casting in Hogwarts. They might also teach the benders some simple spells. Another possibility is a crossover with the world of Twilight. Although it's not as magical in the traditional sense, the OC could interact with the vampires and werewolves. Maybe they could use magic to protect themselves from the vampires' attacks. Or a crossover with the Percy Jackson universe. The OC could visit Camp Half - Blood and share their knowledge of wizardry with the demigods.
A cool Harry Potter OC Crossover Fanfiction idea could be to have an OC crossover with the world of Middle - earth. Imagine an OC from Hogwarts traveling to Middle - earth and using their magic to help in the battles against Sauron. They could introduce wands and spells to the hobbits and elves. Also, a crossover with the world of Fairy Tail would be interesting. The OC could join the Fairy Tail guild and participate in their quests while also showing off the unique magic of the Harry Potter universe. And a crossover with the world of Howl's Moving Castle could be fun too. The OC could interact with Howl and Sophie and learn about their form of magic which is different from Hogwarts magic.
One idea could be an SI (self - insert) who has the power to manipulate time enters the Harry Potter world. They could use their power to prevent certain tragedies, like Sirius's death. Another could be an OC (original character) with the ability to communicate with magical creatures. They team up with Harry and friends to uncover a plot that involves the Forbidden Forest's creatures being used by dark wizards. And an SI who is a master of potions from a different magical world comes to Hogwarts and starts creating new and powerful potions that help in the fight against Voldemort.
Well, an interesting concept for a Harry Potter OC fanfiction could be an OC who is a time - traveler. They could go back in time and interact with the founders of Hogwarts, or forward in time to see the future of the wizarding world. Also, an OC that is a magical creature hybrid, half - human and half - something like a centaur or a mermaid, could bring a lot of unique storylines. Additionally, an OC who is a secret heir to one of the old wizarding families and has to navigate the politics and secrets of that family would be really engaging.
Maybe the aunt is a half - blood who has a foot in both the Muggle and wizarding worlds. She could be an artist who uses magic in her art, creating paintings that come to life. In fanfiction, she could help Harry see that there are different ways to use magic beyond just spells for combat or everyday tasks, and she could also be a source of comfort during his tough times at Hogwarts.
One idea could be that Merlin somehow gets transported to the Harry Potter universe. He could use his magic, which is different from the wizarding magic in Harry Potter, to solve some of the mysteries or problems there. Maybe he teams up with Harry and helps him defeat Voldemort in a unique way, like using his ancient magic knowledge.
One interesting idea could be a crossover with a fairytale world. For example, Hermione could be transported to a world like Cinderella's and meet a prince who has some magic similar to that in the Harry Potter universe. This would create a new kind of romantic dynamic where she has to balance her Hogwarts knowledge with this new, more traditional fairy - tale romance.
One idea could be that Hogwarts students discover Pokemon in the Forbidden Forest. They could start training them as part of a new magical - creature - handling class. Another idea is that a powerful Pokemon like Mewtwo ends up at Hogwarts and causes chaos among the students and teachers, who have to use their magic to deal with it. Also, a wizard could accidentally cast a spell on a Pokeball and create a new, hybrid Pokemon - magic creature.
In a Bleach and Harry Potter crossover fanfiction, it could be fascinating if the Quidditch players in Harry Potter had to face off against Hollows during a game. Imagine the chaos! Or perhaps the magic spells in Harry Potter could be used to enhance the powers of the Soul Reapers in Bleach. For example, a spell could be used to strengthen the bond between a Soul Reaper and their Zanpakuto. And if the Triwizard Tournament had a special task where the contestants had to team up with a Bleach character to defeat a powerful combined threat of a Dark wizard and a powerful Hollow.
One idea could be to have a wizard from the Harry Potter world time - travel to the Tudor era. Maybe they get mistaken for a sorcerer or a prophet. Another could be to have a Tudor character discover a hidden wizarding school in England during that time. They could then learn some basic magic and use it to their advantage in the Tudor court politics.
In a crossover, the underworld could have its own form of magic that is different from the magic in the wizarding world. Ron could be the one to first discover a connection between the two magics. He might find an old artifact in the wizarding world that has a link to the underworld. This could lead to an adventure where the trio explores the underworld to prevent a dark magic from the underworld from spreading into the wizarding world.
One idea could be to have the Gallagher family from 'Shameless' somehow end up at Hogwarts. Maybe Fiona could be mistaken for a new teacher and cause chaos in the school with her no - nonsense attitude. Another could be Lip getting involved in a magical experiment gone wrong with Hermione. He might use his street - smart knowledge to help her out in a different way than she's used to.