Well, in some 'Harry Potter and Final Fantasy 7 fanfiction', there could be a fusion of the two storylines' themes. The fight against the Dark Lord in Harry Potter is similar to the battle against Sephiroth in Final Fantasy 7. So, a fanfic might show the characters from both universes joining forces to fight a common evil. Maybe Cloud and Harry Potter teaming up, with Cloud's sword skills and Harry's magic making them a formidable duo.
One interesting crossover could be the use of magic spells from Harry Potter in the world of Final Fantasy 7. For example, a character might use 'Expelliarmus' to disarm a Shinra soldier. Another could be the appearance of Final Fantasy 7 creatures in Hogwarts. Imagine a Chocobo running around the Quidditch pitch! Or perhaps a character from Final Fantasy 7 attending Hogwarts and having to learn about magic while also using their own unique abilities.
One interesting crossover could be the use of magic systems. In Harry Potter, magic is more about spells and incantations, while in Final Fantasy 12 there are various magicks like black, white, and green magick. A fanfiction could explore a character from Harry Potter learning the magick system of Final Fantasy 12, perhaps Hermione trying to study the more scientific approach to magic in Final Fantasy 12.
One interesting crossover could be the use of magic spells from 'Harry Potter' in the world of 'Final Fantasy XV'. For example, a character from 'Final Fantasy XV' might learn the Patronus Charm to fend off daemons. Another could be the appearance of Hogwarts - like buildings in the 'Final Fantasy XV' landscape. Maybe Noctis and his friends could attend a magical school similar to Hogwarts.
One interesting crossover could be the use of magic systems. In Harry Potter, magic is mainly done through wands and spells, while in Final Fantasy X, magic is more about summoning and using different elements. A fanfiction might combine these, like having a wizard in the Harry Potter world learn to summon aeons from Final Fantasy X.
Well, in some fanfictions, the characters' personalities might be combined. Cloud from Final Fantasy VII could be a student at Hogwarts with his brooding personality. He might be in Slytherin, using his skills with a sword (which could be magically enhanced) to protect the school. And Hermione could find herself interested in the technology of the Final Fantasy VII world, trying to figure out how the materia works and if it could be used in the wizarding world to enhance magic.
A cool crossover might involve the jutsu in Naruto being combined with the spells in Final Fantasy 14. Picture Sasuke using a spell like Blizzard III from Final Fantasy 14, but with his own Uchiha - style twist. Also, the ninja villages in Naruto could be compared to the city - states in Final Fantasy 14. The fanfiction could explore how the politics and power dynamics of both worlds interact when characters from each are forced to cooperate. Maybe the Hidden Leaf Village and Limsa Lominsa form an alliance to fight a common enemy that threatens both their existences.
One interesting crossover could be the characters from Naruto using the Materia from Final Fantasy 7. For example, Naruto with the Fire Materia could enhance his Rasengan with fire elemental powers. It would be a really cool visual to see.
One interesting crossover could be the combination of RWBY's unique combat styles with Final Fantasy's magic systems. For example, Ruby's scythe - wielding skills might be enhanced with some of Final Fantasy's fire or ice magic spells. It would create really dynamic and visually stunning fight scenes.
Well, in some fanfiction, we might see Anna and Kristoff visiting Hogwarts. They could be amazed by the moving staircases and magical creatures. In reverse, Harry, Ron and Hermione could end up in Arendelle. Hermione might be intrigued by the way Elsa controls her ice powers and try to find a scientific or magical explanation for it. Also, the Dementors from Harry Potter could be compared to the dark forces in Frozen 2, like the mist that Elsa has to face.
One interesting crossover could be the use of magic in the Avengers world. For example, Hermione could use her knowledge of spells to help the Avengers solve a problem that technology couldn't. Maybe she could use a spell to break through an impenetrable force field created by an enemy. Another aspect could be the Avengers characters learning magic. Tony Stark might be fascinated by the concept of magic and try to incorporate it into his technology. Or Thor could share his knowledge of Asgardian magic with the Hogwarts students.
One interesting crossover could be a scenario where Hermione uses her magic to help Elsa control her powers better. Maybe she creates a spell that can soothe Elsa when she's about to lose control.