Well, it could be that Harry Potter uses his magic skills like the Patronus charm against Thor's lightning. Maybe Thor mistakes Harry's magic for some new Asgardian sorcery at first. And then they start to fight over some misunderstanding, like a magical artifact that Thor thinks is from Asgard but Harry knows is important for the wizarding world.
The plot might involve a magical realm that somehow connects Asgard and the wizarding world. Harry Potter is drawn into it while Thor is there on a mission. They cross paths and due to their different ways of handling things and protecting their worlds, they end up in a fight. Harry could be using spells like Expelliarmus while Thor throws his hammer at Harry, who then uses a Shield Charm to defend.
In this fanfic, perhaps there's a villain who tricks them into fighting each other. The villain spreads false rumors that Thor is after Hogwarts' secrets and that Harry Potter is a threat to Asgard. So, Thor attacks Harry, who tries to reason with him at first but then has to defend himself. Harry's knowledge of the wizarding world's hidden places could give him an advantage in the fight as he can use the terrain to his benefit while Thor has his brute strength and lightning powers.
One possible plot could be that Thor somehow gets transported to the wizarding world. He might initially be confused by the magic there as it's different from his Asgardian powers. Harry Potter and his friends could be intrigued by Thor and his hammer. They might team up to fight a common enemy, perhaps a dark wizard who has somehow got hold of some Asgardian artifact and is misusing its power.
One possible plot could be that Thor ends up in the wizarding world of Harry Potter. Maybe the Bifrost malfunctions and he lands near Hogwarts. He could be mistaken for a very powerful wizard at first. Then he teams up with Harry Potter and his friends to fight against a new dark threat that is using both magic and some form of Asgardian - like power. Thor could teach the wizards about Asgardian combat and they could teach him more about the nuances of magic.
Well, it could be about a character who is the daughter of Thor and somehow gets involved in the Harry Potter universe. Maybe she has special powers from being Thor's daughter like super strength or the ability to control lightning, and she uses these powers to help Harry and his friends in their battles against the dark forces in Hogwarts.
Well, perhaps the plot could involve Harry having to deal with the dual nature of his heritage. He might inherit Thor's strength and Hela's connection to the darker aspects of magic. Maybe he has to face off against enemies that are threatened by his unique lineage and the power it could bring. He could also struggle with fitting into both the wizarding world of Harry Potter and the Norse mythology - influenced world of his parents.
Well, one possible plot could be that the demigod, as a son of Thor, brings his Norse powers to the wizarding world of Harry Potter. He might use his lightning - based powers to fight against dark wizards. Maybe he teams up with Harry and his friends, and his unique abilities give them an edge in battles, like when facing Voldemort's Death Eaters.
One idea could be that the Avengers find themselves magically transported to the wizarding world. Thor, with his Asgardian magic, might have an interesting interaction with the Hogwarts professors. Maybe they team up to fight a new, combined threat that is both magical and technological.
Well, it could be really cool. Harry might have Thor's strength and his connection to lightning. Maybe he could use his magic wand in a way similar to how Thor wields Mjolnir. For example, instead of just casting spells, he could channel Thor's power through the wand to create more powerful magical effects.
A powerful dementor - like being that has been corrupted by Asgardian dark magic. This entity could be draining the life force of both wizards and Asgardians. It would be up to Thor and Harry Potter to find a way to stop it, as it poses a threat to both of their worlds.
Well, perhaps there's a magical portal that connects the Ghostbusters' New York City to Hogwarts. And some mischievous Hogwarts ghosts accidentally pass through it and start causing chaos in NYC. The Ghostbusters, not knowing anything about magic at first, have to team up with Harry Potter and his friends who come to NYC through the portal to figure out how to send the ghosts back. They learn from each other's worlds in the process.
Well, one possible plot could be that they meet during a time when the wizarding world is facing a new threat. Harry, being the hero he is, is in the thick of things. Daphne, perhaps having changed from her Slytherin ways a bit, starts to see Harry in a new light. They team up to fight the threat, and along the way, their relationship blossoms into love. Eventually, they get married and work towards a more united wizarding world, where Slytherin and Gryffindor ideals are combined to make it a better place.