Maybe a new character could be a ghost from a long - forgotten part of the Ghost Zone. This ghost has been asleep for centuries and wakes up in Danny's time. It has powers that are completely unknown to Danny and his friends, and it has its own motives and goals that might conflict or align with Danny's.
A new character could be a half - human, half - ghost like Danny, but from a different part of the world with unique cultural ghost powers. For example, a character from Asia who can use ancient ghost - binding spells passed down through generations in their family.
There could also be a new ghost hunter character. This person could be an expert in a different type of ghost - hunting technology, like one that can disrupt a ghost's energy signature in a completely new way. They might start off as an adversary to Danny but later become an ally.
There could be a character like Nova, a young girl who has the ability to phase through solid objects like a ghost but is human. She uses this power to help the new generation of ghost hunters.
Maybe a new student who has some psychic abilities that attract the attention of the ghosts in the school. This student could either be a friend or a foe to Danny, depending on how the story unfolds.
Obviously, Danny Phantom himself. And Hades, his supposed father. There could also be Danny's friends like Sam and Tucker. Maybe some Greek mythological figures such as Cerberus, the three - headed dog that guards the underworld.
An ancient spirit that has been trapped in the urban jungle for centuries. It has its own motives and goals, and at first seems like a foe but later might become an ally to Danny.
One idea could be exploring Danny's life after he has fully mastered his ghost powers. He could be facing new, more powerful ghost threats that require him to use his powers in creative ways. For example, a group of ancient ghosts that have a connection to the very origin of the Ghost Zone.
Potential characters could include powerful ghost lords that Danny has to deal with. These could be ancient and very powerful ghosts who see Danny as a threat or an opportunity. There might also be some half - ghost characters like Danny, but with different origins. They could be his allies or enemies. And let's not forget the minor ghosts that populate the Ghost Zone, they could add flavor to the story, either by helping Danny or causing trouble for him.
Well, for the Danny Phantom side, Sam and Tucker could be involved. Sam might be jealous at first when other girls start showing interest in Danny. Tucker could be the one giving Danny advice on how to handle the harem situation. From other shows, if it's a crossover with a magical girl anime, characters like Sailor Moon could be part of the harem. Her kind and powerful nature would make an interesting dynamic with Danny. Another could be Kim Possible. She's a strong and capable girl who would likely be intrigued by Danny's powers and get involved in his adventures, and potentially develop feelings for him.
A new character could be a foreign hero who comes to Amity Park to learn from Danny. They might have different powers and a different approach to ghost - fighting. Another possibility is a scientist who is intrigued by Danny's powers and wants to study him, not in a malicious way, but out of pure scientific curiosity.
Sam and Tucker would definitely be his top allies. They've been with Danny through his whole journey as a half - ghost, and they'd support him in his new role as the Master of Death. Sam could offer her unique perspective on the moral and ethical side of things, while Tucker could use his tech skills to help Danny understand any new powers or situations related to his new title.
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.