There might be. Fanfiction writers love to experiment with different ideas regarding their favorite characters. Changing Danny Phantom's body to be feminine could be a way to explore different storylines, such as how he would interact with other characters in this new form or how it would affect his powers and relationships.
One possible plot could be Danny adjusting to the new body and the reactions of his friends and family. Maybe they initially have a hard time accepting it, but over time come to terms with it.
One idea could be exploring what would happen if Danny had a different body form due to a ghostly experiment gone wrong. For example, his body could be part human, part animal ghost hybrid, which would bring a whole new set of challenges and adventures as he tries to hide this new form from his friends and family while still fighting ghosts.
AO3 is a great place to find 'Danny Phantom Prince Fanfiction'. It has a tagging system that allows you to narrow down your search specifically for stories about Danny being a prince. Fanfiction.net also has a good amount of these types of stories. You can also try searching on Tumblr. Sometimes, fans will post links to their 'Danny Phantom Prince Fanfiction' on their blogs or in relevant Tumblr groups.
One idea could be that Danny possesses someone to experience a normal day at school without his ghostly powers causing chaos. He could learn about the simple joys and struggles of being a regular human for a day.
One possible antagonist could be Vlad Masters. He might want to keep Danny's body for his own evil purposes, like using it to gain more power or to take over Danny's life. Another could be a powerful and vengeful ghost who has a grudge against Danny and sees his body as a way to get back at him.
Well, it could be that Danny has been separated from his body for a long time in the fanfiction. When he finally locates it, his body might be in a weakened state. He might need to use his ghost powers in creative ways to revive and reunite with his body. There could also be some emotional moments as he reflects on how much he's missed being in his own physical form.
A good place to start looking for the 'danny phantom mother of a phantom fanfiction' would be dedicated Danny Phantom fan sites. These sites often have a section for fanfiction, and it's likely that if this fanfiction exists, it will be there. Another option is to ask in Danny Phantom fan forums. The fans there might know where to find it or might even be able to share it with you if it's not publicly available on the usual platforms.
You can find Danny Phantom and Danielle Phantom fanfiction on fanfiction.net. It has a large collection of stories related to the Danny Phantom series, including ones focused on Danielle. Another good place is Archive of Our Own (AO3), which also has a variety of fan - created stories about these characters.
In this fanfiction, it could be that Danny Phantom meets a Danny Phantom from a parallel fan - made story. At first, they don't trust each other. But as they learn more about each other's worlds, they realize that there are some common elements that are being threatened. It could be that a powerful ghost is trying to rewrite all the fanfic universes related to Danny Phantom. So, they must combine their strengths and knowledge to stop this from happening.
Well, in this kind of fanfiction, Danny could be controlled by an ectoplasmic parasite. The parasite latches onto Danny and takes over his actions. His eyes might glow a different color to show he's not in control. His friends would first be confused, then realize something is amiss and start investigating.