A crossover could also be based on a character's curiosity. Let's say Luna Lovegood is always interested in strange and magical things. She hears about Hotel Transilvania and decides to visit. Once there, she starts to study the different magical creatures and their cultures. Her unique perspective from the Harry Potter world could lead to some interesting interactions and storylines. She might even introduce some of her own magical items or spells to the residents of the hotel.
One way it could work is through a common enemy. Suppose there's a dark force that threatens both the wizarding world of Harry Potter and the world of Hotel Transilvania. The characters from both universes would have to team up to defeat it. The wizards could bring their knowledge of spells and magical defenses, while the creatures in Hotel Transilvania could use their unique physical abilities. It would be a story full of action and cooperation between very different characters.
One great fanfiction could be about how the magical world of Harry Potter intersects with the spooky yet fun world of Hotel Transilvania. Maybe Harry and his friends end up at the hotel during a wizarding world tour. They could encounter the hotel's unique characters and get into all sorts of adventures, like helping Dracula deal with some dark magic that has seeped into his hotel from the wizarding world.
Well, a simple way could be through a portal. Imagine a magical portal opening between the mutant world and the wizarding world. Magneto steps through and is immediately in Hogwarts. The students and teachers are both fascinated and terrified. Harry Potter, being the brave one, approaches Magneto to find out his intentions. This encounter could spark a whole series of events where they either become friends or enemies depending on how Magneto reacts to the wizarding world's power structure.
One way a Death Note and Harry Potter crossover could work is by having a Death Note fall into the wizarding world. Maybe a Muggle - born student discovers it and starts using it to deal with dark wizards in secret. However, they soon realize the moral and ethical implications are just as complex as in the original Death Note story.
It could work by having a magical event that blurs the boundaries between their two worlds. For example, a powerful spell gone wrong could open a portal between the wizarding world and the world of the vampires. Elijah, being curious and always looking for new things, would be drawn to this new world. He and Harry would then meet and their different skills and personalities would create interesting storylines.
It could also work through a shared threat. Imagine a villain who has both magical and scientific powers is threatening both the wizarding world and Central City. Harry Potter and Barry Allen are brought together by their need to stop this villain. Harry uses his spells and knowledge of the wizarding world, while Barry uses his super speed and scientific know - how. They have to learn to trust each other despite their different backgrounds and ways of doing things. For instance, Barry might be initially skeptical of magic, but as he sees it in action, he starts to respect it more.
Well, it could work by having a magical portal connect their two worlds. Vincent could step through it into the wizarding world. Then he would have to adapt to the rules of magic there. He might be confused by things like wands and spells at first, but his combat experience would be useful. For example, when facing a horde of Dementors, he could use his fast reflexes to fend them off while Harry uses his Patronus charm.
Well, one way it could work is through magic. Harry Potter has his own set of magical abilities, and Wolverine has his mutant powers. If Harry were his son, perhaps he could inherit a combination of both. For example, he could use magic to enhance his physical abilities like Wolverine's. He might be able to use spells to heal himself even faster than normal wizards, taking advantage of Wolverine's rapid healing factor. Also, his fighting style could be a blend of wizard dueling and Wolverine - style brawling.
A crossover could function through a portal or some sort of magical event that links the two worlds. For instance, the Tesseract in the Avengers universe could malfunction and open a portal to the Harry Potter world. Then, the Avengers find themselves in a world full of magic and wizards. They soon learn about the God of Death and realize that they need to work with the wizards like Harry, Hermione, and Ron to stop this ultimate force. The Avengers' powers would be a new and strange thing in the Harry Potter world, and the wizards' magic would be equally fascinating to the Avengers.
Another way it could work is through a character's quest. Let's say a character in the Harry Potter world is searching for a way to defeat a new kind of dark magic that has some similarities to the dark forces in Selene's world. They travel to find Selene, and together they combine their knowledge and skills. Selene's knowledge of the underworld's dark secrets and Harry's understanding of magic could create a unique way to fight this new threat.
Well, Naruto, being godlike, might have a different perception of the monsters in Hotel Transylvania. He could see their potential and start training them in his ninja ways. Dracula could be hesitant at first but then see the benefits. Meanwhile, the hotel's unique environment could also affect Naruto. Maybe the magic there could enhance his powers in some unexpected ways, leading to new forms of his jutsu. This would create a dynamic where both sides are influencing each other in the fanfiction.