Perhaps there could be a love interest that is unique to his female form. Maybe someone who didn't notice Danny before as a boy, but now is attracted to him as a girl. This could add a whole new layer of drama and romance to the fanfiction, as Danny has to figure out how to handle this new relationship while still dealing with his ghost - hunting duties.
Perhaps in this fanfiction, Danny as a kid would have a different perspective on the ghost world. He might be more curious and less jaded. His appearance as a kid could also change how the ghosts interact with him. Some ghosts might underestimate him, which could be an advantage for Danny. He could use this to his benefit when dealing with them, while also trying to figure out how to turn back to his normal self.
One idea could be that Danny turns into a girl due to a ghostly spell gone wrong. In the fanfiction, he could struggle with the new body while still having to fight ghosts. Maybe his friends don't recognize him at first, leading to some comical and tense situations.
He could be in a situation where he's trapped in the Ghost Zone. His friends might have to figure out a way to get to him. They could use some of Tucker's new inventions, like a Ghost Zone - traversing vehicle. They'd face many challenges along the way, such as avoiding other dangerous ghosts.
Well, one possible plot could be that Danny, while on an underwater mission to stop some ghostly threat near the ocean floor, gets hit by a strange spell or artifact that turns him into a mermaid. He then has to deal with his new form while also trying to keep his ghost - fighting duties going. Maybe he discovers new powers related to his mermaid form that help him in his battles.
She could face a lot of challenges. For example, she might be shunned by some in the ghost world because of her half - human heritage from Danny. Or she could struggle to fit in with humans because of her ghostly powers. It would be a complex situation for her to navigate.
Danny could use his ice powers to create ice shields during battles. This would give him an extra layer of protection against his enemies' attacks.
In 'Danny Phantom Goes to School' fanfiction, there could be a new character who is also a half - ghost and they become friends or rivals with Danny. They could team up to fight a powerful ghost that has infiltrated the school's science lab. The school setting also allows for some interesting interactions between Danny's human friends and his ghost - hunting side. For example, his friends might accidentally discover his secret identity while they are all involved in a school project.
In the fanfiction, they could team up. Jack has all his ghost - hunting gadgets and Danny has his ghost powers. They could use their combined skills to fight a common enemy, perhaps a more powerful ghost that neither could handle alone. It could be a start of a new alliance between them.
In a fanfiction, if Danny overshadows Sam, he might be trying to protect her from a danger she's unaware of. Maybe there's a ghost that's targeting Sam, and Danny can't be with her all the time, so he overshadows her to give her the ability to defend herself. He could transfer some of his ghost powers to her for a short time. This would create a lot of drama and action in the story, with Sam having to figure out these new powers while still being herself at the core.
Well, in such a fanfiction, Danny Phantom might be in a really tough situation. Walker is a powerful foe. He could be locked up in Walker's prison dimension, facing all kinds of strange and dangerous inmates. Maybe he'd be trying to find a way to escape using his ghost powers, but Walker has probably set up all sorts of barriers to prevent that.