Fanfiction ideas combining Harry Potter and Black Butler
One idea could be a crossover where the characters from Harry Potter end up in the world of Black Butler. For example, Harry, Hermione and Ron could be mistaken for some kind of strange magical beings in the Victorian era of Black Butler. They might be brought to the Phantomhive manor and Sebastian has to figure out what to do with them. Maybe they are there to solve a mystery that involves both the magic of the Harry Potter world and the dark secrets in the Black Butler universe.
A third idea is that the Death Eaters from Harry Potter team up with some of the villains in Black Butler. Voldemort could be interested in the power that the demons in Black Butler possess. He might send some of his Death Eaters to make a deal with the demons. This would create a very dangerous situation where the heroes from both worlds, like Harry Potter and Ciel Phantomhive, have to join forces to stop this unholy alliance.
Fanfiction ideas combining Harry Potter, Avengers, and Black Widow
In a fanfiction, the Avengers could be called to the Harry Potter universe to help fight Voldemort. Black Widow would be a key player in infiltrating Death Eater strongholds. She could teach the Order of the Phoenix some of her combat and espionage techniques. And perhaps Harry Potter could gain some inspiration from the Avengers' teamwork and use it against Voldemort.
Fanfiction ideas combining Harry Potter and Fluttershy
One idea could be that Fluttershy somehow gets transported into the Harry Potter world. Maybe she arrives at Hogwarts as a new kind of magical creature that the students have never seen before. Her gentle nature might initially cause confusion among the more rowdy students, but she could gradually make friends with the likes of Luna Lovegood, who would be intrigued by her uniqueness.
Fanfiction Ideas Combining Harry Potter and Magneto
Another concept could be that Harry Potter discovers he has a connection to Magneto's mutant powers. This might happen during a strange encounter with a dark magic object that unlocks a latent power within him. He then has to learn how to control these new abilities while also dealing with the threats in his own wizarding world, and he might seek out Magneto for guidance in a secret meeting across the boundaries of their two worlds.
Fanfiction ideas combining Harry Potter and Kakashi
One idea could be a crossover where Kakashi is summoned to the Harry Potter world by a dark magic spell gone wrong. He then uses his ninja skills and Sharingan to navigate the wizarding world, perhaps even teaching some Defense Against the Dark Arts classes with his unique combat knowledge.
Fanfiction ideas combining Harry Potter and Megatron
Maybe in a fanfiction, Harry Potter and his friends accidentally stumble upon a hidden Cybertronian relic. This relic has some sort of power that attracts Megatron. Harry and his friends then have to defend the relic from Megatron while also trying to figure out what it does and how to use it to their advantage in the fight against Voldemort.
Fanfiction ideas combining Harry Potter and Whitebeard
One idea could be a crossover where Harry Potter accidentally travels to the One Piece world and meets Whitebeard. He could learn about their different forms of magic and power, and together they face a new threat that combines the dark magic from his world and the powerful pirates in the One Piece world.
Fanfiction ideas combining Harry Potter and Ranma 1/2
One idea could be a crossover where Harry Potter accidentally ends up in the world of Ranma 1/2. Maybe he's on a magical experiment gone wrong and lands in Nerima. He could use his magic to help Ranma deal with his curse, like creating a spell to keep him from changing into a girl when splashed with cold water.
Fanfiction Ideas Combining Harry Potter and Android 18
Another concept could be a crossover where the magic in the Harry Potter universe has an unexpected effect on Android 18. For example, it could start to interact with her android systems in strange ways, giving her new powers or abilities that are a combination of magic and her android technology. This would lead to a whole new set of adventures as she tries to figure out what's happening to her.
Fanfiction ideas combining Harry Potter and Gandalf
One idea could be that Gandalf somehow gets transported to the Harry Potter universe. He could become a mentor to Harry, using his vast magical knowledge and wisdom from Middle - earth. Maybe he helps Harry understand some ancient magic that even Dumbledore wasn't fully aware of.
Fanfiction ideas combining Harry Potter and Hawkgirl
One idea could be that Hawkgirl somehow gets transported to the Harry Potter universe. Maybe she arrives during a Quidditch match and her flying skills astound everyone. She could then join forces with Harry and his friends to fight against the dark forces in Hogwarts, using her Nth metal mace and flight abilities in unique ways.