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.
In this fanfiction, it could center around Kakashi's daughter growing up without a mother figure. So Kakashi has to play both parental roles. He struggles at first but eventually learns how to be there for her in all aspects of her life, from her first crush to her first difficult mission.
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.
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.
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.
Maybe an organization that wants to use her unique abilities. If she has inherited some special power from Kakashi or has her own distinct skills, an evil organization could try to capture her and force her to work for them. They would be the main obstacle she has to face in the story.
Well, obviously there's the father and the daughter. The father is often portrayed as a strong, protective figure. He might be a skilled warrior or a wise leader in the story's context. The daughter is usually depicted as a young, growing character. She could be curious, with a thirst for knowledge or adventure. There might also be other family members or friends in the story. For example, an aunt or an uncle who play supporting roles in the relationship between the father and daughter.
It could be an original character created just for the fanfiction. Maybe a mysterious ninja woman who crossed paths with Kakashi during a mission and they had a brief but intense relationship.
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.
It could be a new group of rogue ninjas who oppose the ideals of the Hidden Leaf Village. They might target Kakashi's daughter because of her connection to Kakashi and Naruto, seeing her as a symbol of the village's new generation of strength.
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.