Her character could develop in terms of her magic usage. Instead of using magic in the traditional wizarding way, she'd have to find ways to blend it with the ninja skills. This would require her to be creative and adaptable. She might start to develop new spells or magical techniques that are inspired by the ninja abilities around her. This development would not only make her a more unique character but also help her to better fit into the Naruto universe while still retaining her own identity from the Harry Potter world.
She could become more confident in her new identity. Starting as Harry from a different world, she'd have to adapt to being a ninja and Naruto's sister. This new role would force her to step out of her comfort zone and grow. For example, she might have to learn physical combat skills which she didn't rely on as much in the wizarding world.
Naruto might become more confident. Being a dragon gives him new powers, and with that comes a sense of self - assurance. He may also become more solitary at first as he tries to understand his new form. But as he gets used to it, he'll start to integrate his dragon side with his ninja self.
Naruto could become more confident. With Kushina as his maid, he'd have someone who truly believes in him at home all the time. He might grow out of some of his insecurities faster. For Kushina, she could develop a new sense of purpose. Instead of just being a memory or a lost hero, she's actively involved in Naruto's life again.
In this fanfiction, Naruto might experience some significant character development. He could initially be very confused and conflicted about the situation. On one hand, he has his mother as a servant, which is a strange and uncomfortable idea. This could lead to him being more introspective. As time goes on, he might start to see Kushina's value in a new light, not just as his mother but as someone who is loyal to him in this new role. This could make him more empathetic towards others in servant - like positions. He may also become more decisive in his actions, as he now has someone directly under his authority and has to make decisions regarding Kushina's tasks and well - being.
Well, the plot could involve her adapting to the ninja world. Maybe she'd bring some of her magic knowledge from the Harry Potter universe, like using spells in a new way to mimic ninja techniques. She could also have a special bond with Naruto, being his sister, and help him in his journey to become Hokage, like using her intelligence to outwit enemies.
In this fanfiction, Naruto could develop his skills in a new way. Since he is dealing with a banished Fem Kyuubi, he may have to learn different ways to communicate and work with her. This could lead to him becoming more adaptable. The Fem Kyuubi might develop from a vengeful being into one who is more forgiving. She realizes that not all humans are bad through Naruto's kindness, and this changes her view of the world and herself.
Her character might start off a bit confused. Being in a new world as Naruto's sister, she has to adapt. She could develop a strong sense of loyalty to the Hidden Leaf village like Naruto. And as she grows, she might become more confident in using her magic in this new environment. Maybe she starts off being a bit shy about it but then realizes it can be a great asset.
In such a fanfiction, perhaps the plot could involve fem Harry using her wits to outsmart Voldemort while in the guise of a slave. She might be able to gather information about his plans and pass it on to the Order of the Phoenix. But it's a very dark and unorthodox take on the story. Usually, the Harry Potter story is about good versus evil in a more straightforward way, and this would be a major deviation. There could also be a plotline where Harry tries to find a way to break the slave bond through some long - forgotten magic or ancient spell, which would add an element of mystery and adventure to this rather dark premise.
In this fanfiction, perhaps Naruto's physical abilities are enhanced as the Kyuubi's kit. He might be able to move faster, jump higher, and his strength could be superhuman. Also, his relationship with Sasuke could change. Sasuke might see Naruto as an even greater threat or, on the other hand, an ally he needs to understand better. And Naruto could start to have a different understanding of his own identity and place in the ninja world.
Fem Naruto might develop a more motherly or nurturing side. Kushina was known for her strong personality and also her love for her family. Fem Naruto could inherit some of these traits and become more protective of her friends, almost like a mother figure to them. This would be a significant change from the original Naruto's character in some aspects.
Bella might become more assertive. Since Katherine is a strong - willed character, being her sister could force Bella to grow a backbone. She could start standing up for herself more and not be as meek as she is sometimes portrayed.