His friends Sam and Tucker could be the ones to save him. They are always there for Danny and they might come up with a clever plan using their knowledge of technology and the supernatural world to break into Walker's prison and rescue Danny.
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.
Danny might react with panic at first. After all, he has been hiding his identity from his parents for so long. He could try to escape from them, using his ghost powers in a desperate attempt to get away before they can do anything drastic.
He might meet a nurse who has some sort of psychic ability and can sense that Danny is different. This could lead to an interesting interaction where Danny has to be extra careful.
It could be one of his enemies. For example, Vlad Masters. He has always been envious of Danny and would love to see him in trouble. Exposing Danny's secret would be a great way for him to get back at Danny and take over Amity Park.
Perhaps Danny's friends find out that he has been caught by his parents. They could come to his rescue. Tucker might use his tech - savvy skills to hack into the Fenton's security systems, and Sam could try to reason with Danny's parents. Together, they could try to convince Danny's parents that Danny is still the same person they love, just with some extraordinary powers.
Sam is also quite popular. Her goth - like personality and her strong - willed nature make her an interesting character. In fanfiction, she can be portrayed in different ways, like being even more involved in Danny's ghost - fighting activities.
Another possibility is that he's facing some emotional turmoil. Danny has a lot on his plate. He has to keep his identity a secret from his friends and family, deal with school, and fight ghosts. All this stress could be causing him to lose his appetite. He might be too worried or preoccupied to even think about food.
One possible story could be that Danny is facing a new and extremely powerful ghost. He needs help from his friends Tucker and Sam. Maybe they need to find a rare artifact to defeat this ghost. They could start by researching in the local library, looking through old ghost lore books. Tucker uses his tech skills to try and track down any leads on the artifact's location, while Sam uses her knowledge of the occult.
In addition to the ghosts, there might be some human characters that are important in the 'phantom city danny phantom fanfiction'. They could be Danny's friends or family members who get involved in the events of the Phantom City. Their reactions to the supernatural world and their interactions with Danny and the ghosts would add an interesting dynamic to the story.
One interesting story could be about Danny and Sam going on a ghost - hunting adventure together. They might discover a new type of ghost that has unique powers and they have to figure out how to defeat it using their combined skills.