One interesting concept could be crossovers. For example, Danny Phantom's ghostly powers interacting with the superpowers in the DC universe. Maybe Danny teams up with Superman and they figure out how to use their different powers to fight a common enemy. Another concept might be the reaction of DC characters to Danny's half - ghost nature. Some might be intrigued, while others could be suspicious or even fearful.
One of the popular pairings is Danny Phantom and Raven from Teen Titans. They both have a connection to the supernatural and their personalities can complement each other. Another popular one could be Danny and Superboy. They are around the same age and their powers could create some interesting interactions.
The combination of different power sets. Danny's ghost powers are so unique compared to the powers of DC characters. For example, his intangibility and invisibility can create really cool scenarios when interacting with someone like The Flash.
One really good Danny Phantom DC crossover fanfiction is 'Ghostly Allies in DC'. It starts with Danny being transported to the DC world. He has to figure out how to get back home while also dealing with the various threats in that universe. The author does a great job of making Danny's powers work in the context of DC, and the interactions between Danny and the DC characters are both humorous and engaging.
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.
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 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.
Obviously, the main character would be Danny Phantom himself, but in two different forms or versions. One would be the original Danny Phantom from the canon source, and the other would be a version created by the fanfiction. There might also be his friends like Sam and Tucker who could play important roles in helping the two Dannys understand each other and deal with any issues that arise from their meeting.