There could be some new characters as well. For example, some of Bill's old curse - breaker colleagues. They could bring in new elements of magic and danger. Maybe there's a mysterious wizard who has a vendetta against Bill and sees Harry as a way to get to him, which would make this wizard an important part of the story.
Well, one possible plot could be that Bill takes Harry under his wing after some kind of danger at Hogwarts. He might teach Harry some advanced magic that he learned during his time as a curse - breaker. For example, Bill could show Harry how to deal with ancient and powerful dark magic spells.
Obviously, Harry Potter himself is a crucial character. Then there could be an elder member of the other Potter clan, like an old wizard who has a vast knowledge of the family's history and secrets. There might also be a young Potter relative who is around Harry's age and becomes his new friend or ally.
It could be a new character introduced specifically for the fanfiction. Maybe a mysterious stranger who has some ulterior motives and targets Bill because of his relationship with Harry.
Obviously, Bill and Harry are the main characters. Bill, being the mentor, will play a crucial role in guiding Harry.
Well, aside from the three brothers, there might also be other characters that play important roles. For instance, Ginny Weasley could be in the story as Harry's love interest. Mrs. Weasley would also likely be there, fussing over all of them like a mother hen, making sure they're well - fed and taken care of.
Ron could also play a significant role. He might be torn between his loyalty to Harry and his family and the wizarding world. He could join Harry on his travels for a while, or he could stay behind but still be in contact with Harry, sending him care packages of wizarding treats and useful items.
The hospital staff would surely be important. For example, a kind - hearted nurse who always takes care of Harry and becomes like a mother figure to him. There could also be an old doctor who has seen many strange cases and is intrigued by Harry's situation. Another character could be a fellow patient, a young girl who is also a wizard but has been hidden away in the hospital for a different reason. They could become friends and help each other through their difficult times in the hospital.
A centaur could also be the Guardian of Magic. Centaurs are known for their wisdom and connection to nature. They might see it as their duty to protect magic from being misused by humans. In the fanfiction, the centaur - guardian could use their knowledge of the stars and natural magic to combat the dark wizards.
Obviously, Harry Potter is the main character. He is the one taking on the role of the guardian. Hermione and Ron usually play important supporting roles as well. They help Harry in his mission to protect Hogwarts with their knowledge and skills.
Fleur would definitely be a major supporting character. As Bill's wife, she would play an important role in Harry's new family life. She could teach Harry some French magic or wizarding traditions. The other Weasley siblings could also be supporting characters. They might visit often and continue to be like Harry's extended family. Charlie could come and share his dragon - taming stories with Harry, adding more excitement to Harry's new life.