One plot idea could be that a powerful dark wizard has summoned a Wendigo to Hogwarts to create chaos. Harry, being the hero, has to understand the nature of the Wendigo, which is different from the usual dark creatures he has faced. He might need to seek help from the Forbidden Forest's inhabitants who have knowledge about such ancient and dangerous entities. The Wendigo's connection to the cold and desolate places could also play a role, like it creating frozen areas within Hogwarts that Harry has to navigate through.
Maybe Harry discovers a hidden part of Hogwarts where a Wendigo has been lurking. He has to use his magic skills to either defeat it or find a way to coexist with it.
One idea could be a story where a Wendigo somehow enters the wizarding world of Harry Potter. Maybe it's brought in by a dark wizard who wants to use it as a weapon. The Trio - Harry, Ron, and Hermione - would then have to figure out how to defeat it using their magic and knowledge.
One idea could be a character in the Harry Potter universe who is secretly an Animagus but gets cursed and starts to show Wendigo - like traits. They struggle to control their newfound savage nature while also hiding it from their friends at Hogwarts.
Maybe a spell goes wrong and causes a character to develop diabetes. The story could then be about how they adapt to this new situation. They might search for a magical cure within the wizarding world, or learn to live with it with the help of their friends, like Hermione using her research skills to find suitable magical remedies or ways to manage it.
Perhaps in a 'harry potter yells fanfiction', Harry yells when he discovers that someone has been spreading false rumors about his friends. He could be in the Great Hall, stand up, and yell at the perpetrator, creating a big scene full of drama and conflict within Hogwarts.
One plot idea could be that Tony Stark somehow travels to the wizarding world. He could use his technological knowledge to improve the wizarding devices. For example, he might make brooms fly faster with some kind of engine modification.
Well, one plot idea could be that Harry discovers he has a special gift for breeding magical animals that no one else has. He starts breeding rare and endangered magical creatures secretly in the Forbidden Forest. Eventually, his activities are discovered, but instead of getting in trouble, he is asked to help save the magical animal population in the wizarding world.
One plot idea could be that Harry discovers his new 'God of Mischief' status and uses it to outwit Voldemort in unexpected ways. For example, he could create illusions that drive Voldemort's followers crazy or play tricks on Death Eaters during battles.
One plot idea could be that Henrik Mikaelson somehow gets transported into the 'Harry Potter' universe. Maybe he has his vampire powers and has to hide them among the wizards. He could form an unlikely friendship with Harry and help him in his battles using his unique abilities.
One plot idea could be that Haley Jones is a transfer student from a different magical school to Hogwarts. She could bring with her some unique magical abilities or knowledge that intrigues Harry and his friends. For example, she might know a different type of magic related to time - travel that could help in solving some of the mysteries in the Harry Potter world.
Perhaps Harry discovers he's a shapeshifter early on in his Hogwarts years. He might use this power to play pranks on the Slytherins by changing into a mouse and scaring them in the dungeons. But then, he realizes he has a greater responsibility when he sees the potential of using it against the Dark Arts. For example, he could shift into a large and powerful animal like a hippogriff to fight off Dementors.