Well, in 'Harry Potter Legend of Zelda fanfic', a cool crossover could be the characters swapping roles. Imagine Link using a wand instead of his sword and shield. He could use spells to solve puzzles in dungeons. Or Harry Potter could be on a quest in Hyrule, using his magical knowledge to defeat the likes of Ganon. The magic items from Zelda, like the Ocarina of Time, could have magical properties similar to the Deathly Hallows in the Potter universe.
Well, in some fanfictions, the Triforce from Legend of Zelda could be linked to the magic in Harry Potter. Maybe the power of the Triforce is seen as an ancient and extremely powerful form of magic that some wizards in the Harry Potter universe are trying to understand or control. Also, the creatures from both universes could interact. For instance, a Hippogriff might befriend a Cucco. It makes for really exciting and unique storylines.
One interesting crossover could be the use of magic spells from Harry Potter in the world of Legend of Zelda. For example, a character might use the 'Accio' spell to retrieve a key item in a Zelda dungeon. Another could be the appearance of Zelda characters in Hogwarts. Link could be a mysterious new student who has unique skills with his sword that are both magical and physical, much like some of the wizard dueling skills in Harry Potter.
One interesting crossover could be the use of Naruto's ninjutsu in the world of Zelda. For example, Naruto's shadow clone jutsu might be used to solve puzzles or fight enemies in Zelda's dungeons. Another aspect could be the sharing of character traits. Link's determination and Naruto's never - give - up attitude could combine to create a really strong and inspiring character in the fanfiction.
Some fanfictions might explore the idea of the Triforce in the RWBY universe. Suppose the Triforce represents a powerful force that could either help or harm Remnant. The characters from both worlds would be drawn to it. The Zelda characters, with their knowledge of the Triforce, would have to work with RWBY's Huntsmen and Huntresses to protect it from falling into the wrong hands. There could also be a situation where Zelda's dungeons are reimagined in the RWBY world, and the RWBY teams have to go through them to achieve a certain goal.
One interesting crossover could be the use of magic from Harry Potter in the Avatar world of Legend of Korra. For example, a character might use a spell to enhance their bending abilities. It could create unique and exciting storylines.
One interesting idea could be a crossover with 'Lord of the Rings'. Imagine Harry and his friends in Middle - earth, facing the dark forces there. They could learn new magic from the wizards in Middle - earth or teach their own brand of magic. Another idea is a crossover with 'Percy Jackson'. The demigods and the wizards could team up to fight a common enemy that threatens both the magical and the mythological worlds. Maybe they'd have to combine their powers and strategies.
One interesting crossover could be the use of Stargate's technology in the Harry Potter universe. For example, the Stargate could be a magical object that transports wizards to different wizarding worlds or even other planets. Another idea could be that some Stargate characters end up at Hogwarts and have to learn magic to survive. They might introduce their own technology and knowledge, creating a whole new dynamic within the school.
One interesting crossover could be the use of magic in the Avengers' world. For example, Harry Potter characters could teach the Avengers some basic spells to help them in their battles. Another aspect could be the characters' personalities interacting. Hermione might befriend Bruce Banner and they could exchange knowledge about science and magic.
Well, a crossover could involve the magic of the two universes mixing. In Middle - earth, the magic is more nature - based and ancient, while in the Harry Potter world, it's more structured with spells and potions. If they were combined, new forms of magic could be created. For instance, a spell that uses the power of the ents (from Middle - earth) and the magic of a Hogwarts spell. Also, the different magical creatures could interact. Hippogriffs and eagles from Middle - earth could have some interesting encounters.
A really unique crossover idea in Harry Potter and Batman fanfic could be that the magic in the Harry Potter world starts to seep into Gotham City. Batman has to deal with magical threats that he has never faced before. He might have to team up with some of the Hogwarts students or professors to figure out how to stop the chaos that the magic is causing in his city. This would be a great way to blend the two worlds together and create a whole new set of challenges for Batman.