A crossover with 'Scooby - Doo' could also be really cool. In this fanfiction, the gang and Danny could be investigating a haunted mansion that actually has real ghosts. Danny's knowledge of the ghost world would help the Scooby - Doo gang solve the mystery in a different way than they're used to. His ability to fight ghosts directly would add a new dynamic to their usual mystery - solving routine.
You can start by searching on popular fanfiction websites like Fanfiction.net or Archive of Our Own. Use specific search terms like 'Danny Phantom crossover' along with the name of the other fandom you're interested in. For example, if you want a crossover with 'Avatar: The Last Airbender', search for 'Danny Phantom Avatar crossover'.
One popular Danny Phantom slash fanfiction could be those that focus on the relationship between Danny and his ghostly enemies in a new, unexpected way. For example, some might explore a friendship - turned - more - than - friends scenario between Danny and Dash. It adds a new layer of character development and unique plotlines.
I like the idea of a Danny Phantom and Ben 10 crossover. Ben has the Omnitrix which gives him access to different alien forms, and Danny has his ghost powers. They could either be rivals at first, each thinking their powers are better, or they could quickly team up to face a threat that requires both their unique abilities. It would be a fun clash of two very different power - based universes.
One idea could be that Danny, as a half - ghost, has to prove himself to the Ghost King. Maybe there's a tournament in the Ghost Zone where Danny enters to show his worth. This could lead to some epic battles and alliances with other ghosts.
One idea could be that Danny, with his ghost powers, ends up in the RWBY universe. He could team up with Team RWBY to fight off Grimm that are being influenced by some sort of ghostly energy. His intangibility and flight would be really useful in battles.
First, know the characters well. Danny's personality, his powers, his relationships in the original show are all important. Then, think about the pairing you want to write for. If it's Danny and Tucker in a slash way, consider how their friendship could evolve into something more. Start with a simple idea, like a new ghost threat that forces them to rely on each other in a different way.
In a crossover, characters from the other franchise might betray Danny. For example, if it's a crossover with a show about vampires, a vampire character who seems friendly at first could betray Danny for his ghost powers. They might want to use his powers for their own dark purposes. Another likely candidate could be a character who is jealous of Danny's abilities. Maybe in a crossover with a superhero world, a sidekick who feels overshadowed by Danny's powers and popularity might be the one to betray him.
One idea could be a crossover where the magical world of Harry Potter intersects with the ghostly realm of Danny Phantom. Maybe Danny gets accidentally transported to Hogwarts and has to navigate the strange new world of magic while also dealing with his own ghost powers. He could form an unlikely friendship with Harry Potter and together they face a new threat that combines elements from both their universes.
I think Danny Phantom crossover fanfictions can be really exciting. They bring together different universes and characters, creating unique and unexpected storylines. For example, a crossover with a superhero universe could lead to Danny teaming up with other heroes to fight a common enemy. It's a great way to explore new character dynamics and expand the Danny Phantom world.