Danny is the central character as it's his secret that is being revealed. His friends Sam and Tucker are also main characters. Sam is the goth girl who is always by Danny's side, and Tucker is the tech - savvy friend. If the story involves Danny's love life, then any potential love interests could also be main characters. And we can't forget about Danny's ghostly enemies, like Vlad Plasmius. If the secret is revealed during a battle with him, he would be a significant part of the story as well.
Another interesting point could be Danny's own internal struggle. He has been living a double life, and now that it's all out in the open, he might have to re - evaluate who he is. Does he still want to be a hero? How will he deal with the public's reaction, if the public in the fanfiction world also gets to know about his identity? It could lead to a great character - development arc for Danny in the fanfiction.
In addition to Danny and his immediate circle, there could be other characters from the Danny Phantom universe. For example, Valerie Gray. If she discovers Danny's identity, she might have a complex reaction. On one hand, she's been hunting ghosts, but on the other, Danny has also been protecting the town. So, her role in the fanfiction could be very interesting, especially in terms of how she interacts with Danny after the identity reveal.
The main character is Danny Phantom himself. He's at the center of the story as he discovers and wields the secret weapons. Then there's Vlad Masters. He could be a key character in some fanfictions as he might be after the same secret weapons as Danny, either to use them for his own gain or to stop Danny from having them. Danny's parents also play a role, as their ghost - hunting knowledge and equipment could be related to the secret weapons in some way.
Obviously, Danny Phantom himself is the central character. His friends like Sam and Tucker are also often involved. They play important roles in how Danny deals with his revealed identity, either by providing support or getting into trouble because of it.
Well, one interesting plot could be Danny finally revealing his secret to his best friend Tucker in a really dramatic way. Maybe it's during a ghost attack and he has no other choice but to show his powers to save Tucker. Another plot might involve Danny's parents finding out his secret through some accidental discovery in their own ghost - hunting experiments.
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.
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.
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.
Obviously, Danny Phantom and Dan Phantom are the main characters. Danny is the original form, a heroic character, and Dan is his more evil and powerful transformation.
His friends like Sam and Tucker are likely to be main characters too. They usually support Danny in his adventures and add a human element to the story. Sam with her gothic style and strong will, and Tucker with his tech - savvy skills are important parts of Danny's world.