Danny's parents could also be part of the story in an interesting way. Their obsession with ghosts might accidentally interfere with Danny's attempts at romance. For example, they could set up some kind of ghost - hunting event that gets in the way of Danny's date, or they could unknowingly chase away Danny's love interest if she has any ghostly traits that they misinterpret as a threat.
Maybe Danny tries to use his ghost powers to impress the girl he likes in a 'Lucky in Love' scenario. However, his powers go a bit haywire and instead of impressing her, he makes a fool of himself at first. But through his honesty and determination, she eventually falls for him.
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.
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.
Danny is obviously one of the main characters. He is the half - ghost around whom the whole story revolves. His love interest, whoever that may be in the story, is also a main character. It could be a girl from his school, for example, who gradually discovers Danny's secret and gets involved in his world of ghosts and adventures.
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.
In many fanfictions, there could be new characters created specifically for the Renegades. These might be other half - ghosts or humans with special abilities that complement Danny's. For example, a character who can manipulate time in a small way to help the group in battles.
Jazz, Danny's sister, often plays an important role. She might use her psychological knowledge and her understanding of Danny to try to solve the mystery of his disappearance. And of course, some of Danny's ghostly foes might also be involved, as their actions could be related to his vanishing.
Well, clearly Danny Phantom is likely to be one of the main characters. And since it's about devils, there must be some devil characters as well. Maybe there's a lead devil character that Danny has to face off against.
Well, obviously the twins would be main characters. They could be named something like Jake and Jill. Danny himself would also be a main character as he would likely be involved in their story, either as a mentor or a friend. Then there could be other recurring characters from the original Danny Phantom series like Sam and Tucker, who might help the twins adjust to their new situation.