One idea could be that Danny's ghost powers start to malfunction in the TMNT's dimension, causing strange ghostly events that the turtles have to help him fix. Another could be a villain from Danny's world teams up with one of the TMNT's foes, forcing the two groups to work together. Maybe Danny accidentally gets sent to the sewers where the turtles live and they initially mistake him for a new type of mutant.
Danny and Leonardo would be really interesting. Leo's leadership skills could clash or complement Danny's more impulsive heroics. Also, Donatello and Danny could have some great exchanges as Donnie is into technology and Danny has his high - tech Fenton gear. They could compare notes on their gadgets.
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.
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.
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.
A common theme is the struggle between good and evil within Danny. When he's in his evil form in crossovers, it often shows the fight to bring him back to the good side.
A Danny Phantom and Ben 10 crossover fanfiction would be full of action and adventure. The two characters have very different power sets. Danny has his unique ghost powers such as flight, invisibility, and ecto - blasts. Ben, on the other hand, can transform into a variety of aliens with different abilities like Four Arms' great strength or XLR8's super speed. In the fanfiction, they could be brought together by a common enemy that is threatening both the human world and the ghost zone. They would have to learn to work together, with Danny using his knowledge of the supernatural world and Ben using his combat experience from different alien forms. Their combined efforts would make for a thrilling story as they face challenges that neither could overcome alone.
There's a fanfic called 'When Thor Meets Danny Phantom'. In this story, Danny accidentally gets zapped into Thor's realm. It's full of action as Danny has to use his ghost powers while dealing with the new and strange world of Thor. It also has some really funny moments, like when Danny tries to explain his half - ghost nature to Thor.