A really cool time travel fanfic is 'Through Time and Space with Danny'. In this one, Danny is sent into different points in time within the Danny Phantom universe. He meets various versions of his friends and foes from different time periods, which leads to some really exciting adventures and character development. It's full of action and mystery.
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.
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.
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.
In some fanfictions, Danny's mom might find out when she accidentally witnesses Danny transforming into his ghost form. Maybe she walks in on him at a crucial moment.
One possible story could be that Dani travels back in time to prevent a major disaster in the Danny Phantom world. Maybe she goes back to the time when the portal was first opened and tries to stop it, which would change the entire course of events in the series.
One idea could be that Danny gets an illness that affects his ghost powers. For example, he might start losing control over his intangibility or invisibility. This could lead to some really comical or dangerous situations. Another idea is that his friends try to find a cure for his strange ghost - related illness while also keeping it a secret from the town.
One great Danny Phantom Danny Fenton fanfiction is 'Phantom's Memories'. It delves deep into Danny's dual identity struggles in a really engaging way. The author does an amazing job of portraying Danny's emotions as he tries to balance his normal life as Danny Fenton and his heroic duties as Danny Phantom. Another good one is 'Fenton's Secret Revealed'. It takes a different turn by exploring how the people around Danny react when they start to suspect his secret. This fanfiction is full of suspense and keeps you on the edge of your seat.
In a Danny Phantom trans girl fanfiction, Danny could discover her true identity as a trans girl after an encounter with a special ghost. This ghost could be like a spirit guide that shows her visions of who she really is. Danny then has to figure out how to balance her newfound identity with her ghost - fighting duties. She may also have to deal with the reactions of her family, especially her parents who might be initially confused but eventually come around.