It could be her best friend. Her best friend might be the one who accidentally discovers Bella's secret in the fanfiction. And then they have to deal with the situation together, whether it's keeping the secret or helping Bella face whatever the secret entails.
Her family members could also be important characters. If Bella has a secret, her family might be either protecting her secret or be the reason she has to keep it in the first place. For example, her parents might know about a family curse that Bella is starting to show signs of, and they are trying to shield her from the outside world until she is ready to handle it.
There could be a mysterious stranger. This stranger might be related to Bella's secret in some way. Maybe he is from the same world or has the same kind of power as Bella. He could be a guide for Bella to understand her secret better, or he could be a threat, adding a lot of tension to the story.
There could be a dance instructor. Maybe someone who notices Bella's potential even though she's trying to keep her dancing a secret. This instructor could play a key role in her journey as a dancer.
Edward is a likely candidate. Since he is so attuned to Bella, he might pick up on some strange behavior or scent that leads him to suspect she is hiding something.
There could be a female character, Sofia, who is another member of the mafia. She sees Bella as a threat at first, thinking she'll steal her position or the attention of the men in the mafia. But as time goes on, they might form an unlikely alliance. There may also be a young and ambitious mafia underling named Antonio, who is always looking for ways to climb the ranks and his actions often impact Bella's situation in the story.
There could be Edward. Even if Bella is now immortal, Edward might still play a significant role. He could be either her eternal love or her adversary depending on how the fanfiction is written. Another character could be Alice. Since Alice has her own special abilities, she might be there to help Bella navigate the new world of immortality. For example, she could foresee some of the challenges that Bella will face. Also, Jacob might be a main character. His relationship with Bella, whether it's a friendship or something more complicated, could be further explored in the context of Bella's immortality.
There could be Edward. Maybe he is involved in Bella's life with her psychic powers. He might be curious about her abilities or even try to protect her from the consequences of using those powers.
Her best friend could be a main character. This friend could be the one who has always been there for Bella, through all the hardships of her past. They might try to protect Bella from the things that are resurfacing from her past, or they could be the one pushing her to face her past head - on. For example, the friend might find out some new information about Bella's past and decide that it's time for Bella to know the truth, even if it's painful.
There could be a kind teacher who tries to help Bella. This teacher might notice that something is wrong in Bella's life and tries to offer support, like giving her extra food or a listening ear.
Edward Cullen would likely be a main character. His reaction to Bella's situation, whether it's concern for her well - being or struggle with his vampiric instincts around her period blood, could be a major part of the story.
Since it's a fanfic, it might introduce new characters that are unique to this story. There could be a rival within the federal system who is jealous of Bella's new - found status with the badge. Or perhaps there's a mentor - like figure who has been in the federal service for a long time and helps Bella understand the ropes. Another possibility is that there are informants that Bella has to deal with. These informants could be from different backgrounds and have their own motives for helping or hindering Bella in her work with the badge.
There could be her drill sergeant. This person would be tough and no - nonsense, pushing Bella to her limits during training. Another character might be her best friend in the air force, someone who is always there to support her, through the good times and the bad. There could also be a rival, someone who is constantly competing with Bella for promotions or recognition.