There could be a group of friends she makes during her adventures. They could be from different backgrounds and have different skills. For example, one might be a healer, another a tracker. And of course, there could be characters from the existing ninja clans who either support or oppose her. Some of the clan leaders might play important roles as they have their own agendas regarding Madara's legacy. And then there could be a mysterious figure who seems to know more about her father's secrets than she does, and she has to figure out if this person is an ally or an enemy.
Sasuke could be a main character as well. Given his own experiences of being an outcast and having a thirst for power at times, he could relate to Madara in some ways. They might form an unexpected alliance or have a rivalry based on their shared experiences of feeling neglected or misunderstood in the ninja world.
There could be new characters created specifically for the fanfiction. For example, a mysterious old wizard who lives on the outskirts of Neverland and has knowledge about the daughter's true potential. Or a mermaid who befriends the daughter and helps her understand the secrets of the underwater world in Neverland. These new characters could add more depth and variety to the story.
Fluttershy might be a key character. Her gentle and kind personality could have a big influence on Twilight's daughter. The daughter could learn about compassion and caring for animals from Fluttershy. And of course, Rarity could be in it too. Rarity could help the daughter with her appearance and self - confidence, perhaps creating some beautiful outfits for her.
Zuko could be a main character. He might be the uncle figure to Azula's daughter, trying to guide her away from the dark path her mother once walked. He could share his own experiences of redemption and growth with her.
I think Naruto could be one of the main characters. Since he's Kakashi's student, he might have a special relationship with Kakashi's daughter too. Maybe he acts like an older brother to her.
Well, Boruto could be an interesting character. As her older brother, he could be a mentor figure to her, teaching her some of the more advanced ninja techniques he's learned. He could also be protective of her and get into trouble when he tries to defend her honor. Another character could be Sarada. She and Naruto and Hinata's daughter could become good friends, training together and sharing secrets about their families and dreams.
In some of these fanfictions, Ruby can be a popular character. She has her own history with the Winchesters and with the underworld. When a daughter of hell is introduced, Ruby's knowledge and her own motives can make for some interesting plot developments. And then there's also Rowena, a powerful witch. Her magic and her devious nature can create all sorts of trouble and alliances when combined with the presence of a daughter of hell.
Dumbledore could be an important character too. He might be aware of Snape's daughter's existence and see the potential in her relationship with Draco. He could be the one guiding them, or at least observing from afar, making sure their relationship doesn't cause any major disruptions in the wizarding world.
Well, Ron and Harry would most likely be main characters. They're Hermione's best friends, so they'd be right there by her side when she breaks her leg. They'd probably be the ones helping her get to the hospital wing, getting her books for her when she can't walk to the library, and generally just being there for her.
Her best friend could be a main character. This friend might be the first one Lily tells about getting her period and could offer practical advice like which pads are the most comfortable.