A possible crossover could involve the magic systems. Harry Potter has wand - based magic, spells, and potions. Grimm has a different kind of 'magic' in the form of the Wesen's natural abilities. A fanfiction could show how a character from Harry Potter tries to understand and perhaps even learn from the Wesen's magic. Maybe Hermione would be fascinated by the Wesen's natural shape - shifting abilities and try to find a scientific or magical explanation for it in the context of her own magical knowledge.
One interesting crossover could be the use of magical creatures. In Harry Potter, there are creatures like Hippogriffs and House - elves. In Grimm, there are various mythical beasts as well. A fanfiction could explore how the characters from both worlds interact with these creatures. For example, a wizard from Harry Potter might be intrigued by a Wesen (creature in Grimm) that has some unique magical abilities not found in the wizarding world.
The concept of good and evil in both universes could be a great area for crossovers. In Harry Potter, there is the battle between the forces of Voldemort and those who oppose him. In Grimm, there are good and bad Wesen. A fanfiction could bring together characters from both to fight a common evil. For instance, Harry Potter and his friends could team up with Nick Burkhardt from Grimm to take on a powerful dark wizard who has somehow managed to harness the power of some of the most dangerous Wesen.
Another great idea for a fanfiction would be if the Deathly Hallows were actually items from Grimm's Fairy Tales that got lost in the wizarding world. Harry and his friends have to go on a quest to find out their true origins by traveling through different Grimm - inspired locations, like the forest where Hansel and Gretel got lost. This would combine the mystery and adventure elements of both universes.
There are Grimm Harry Potter fanfictions that play with the idea of fate and destiny, similar to how Grimm tales often have a sense of an inescapable fate. For instance, Harry's prophecy could be intertwined with a Grimm - style fate where he has to face a series of trials that are both magical and based on Grimm's dark and moralistic stories. Characters like Hermione could be depicted as a modern - day Grimm hero, using her knowledge to outwit the dark forces. Some fanfictions might also explore how the magic in the Harry Potter world could be affected by Grimm - like curses and blessings, adding a whole new layer of complexity to the story.
One interesting crossover could be the Quirk vs Magic aspect. In many bnha harry potter fanfictions, characters from BNHA like Deku might visit Hogwarts and try to understand magic while the Hogwarts students are fascinated by his Quirk. It makes for a great exploration of two very different power systems.
One interesting crossover could be the use of magic systems. In some fanfictions, the characters might combine spells from Harry Potter with the dragon - related magic in Eragon. For example, a wizard from Harry Potter might learn to communicate with dragons like the characters in Eragon.
One interesting crossover could be Ben using his alien forms to help the students at Hogwarts during a dark wizard attack. For example, his Heatblast form could be useful against ice spells. Another could be Harry Potter using magic to enhance Ben's Omnitrix. Maybe a spell that makes it transform faster or unlock new alien forms.
One interesting crossover could be the use of magic from Harry Potter in the RWBY universe. For example, a character from RWBY might learn how to use spells like Wingardium Leviosa to help in combat or daily tasks. Another could be the Hogwarts houses being applied to RWBY characters, with Ruby perhaps being a Gryffindor due to her bravery.
In some Harry Potter and Riverdale fanfiction, the houses in Hogwarts could be compared to the social groups in Riverdale. For example, Gryffindor's bravery could be related to how the Bulldogs in Riverdale stand up for what they believe in. Slytherin's cunning might be similar to how some of the more devious characters in Riverdale operate. And then there could be a plot where characters from Riverdale are sorted into Hogwarts houses and have to adapt to the new environment based on the traits of their houses.
In Harry Potter and Clannad fanfiction, a great crossover idea is the exchange of character traits. Maybe some of the Clannad characters could be sorted into Hogwarts houses based on their personalities. And vice versa, the Hogwarts students could learn about the strong family and friendship bonds in Clannad. It could also involve a plot where a powerful Clannad character has to deal with the dark magic threats in the Harry Potter universe. This would create a whole new set of challenges and adventures for both sets of characters.
One interesting crossover could be the use of magic systems. For example, how would the Shadowhunter runes interact with Harry Potter's spells? Maybe a character from the Shadowhunter world could find themselves at Hogwarts and be both amazed and confused by the different forms of magic. Another aspect could be the characters' personalities clashing or working together. A brave Gryffindor and a fearless Shadowhunter might team up to fight a common evil that threatens both their worlds.
One interesting aspect could be the contrast in magic systems. In Harry Potter, magic is more about spells and potions, while Starscream has his own set of technological 'powers' in the Transformers universe. A crossover might explore how they interact. For example, how would Starscream react to a wizard's ability to apparate? And how would a wizard deal with Starscream's flight and weaponry capabilities.