One possible plotline could be that the female Kyuubi uses her power and influence to guide Naruto in a different way than in the original story. Naruto, being submissive, follows her advice which leads to new adventures and challenges. For example, she might direct him to explore a different aspect of his ninja training.
One possible plotline could be that fem Naruto has to learn to control the Kyuubi's power in a different way than in the original series. Since she's female, her approach might be more empathetic, and the story could focus on how she forms a deeper connection with the Kyuubi because of this.
One possible plotline could be the two characters starting as enemies or at least with a lot of misunderstandings. As the story progresses, they gradually come to understand and trust each other, and a romantic relationship begins to form.
There could be a plotline where the fem Kyuubi gets into trouble in the village because she's not fully understood as a pet. Naruto then has to defend her and prove that she's not a threat. Also, a plot where they discover a new power together that helps them in a big battle against a new enemy.
Perhaps the plot could revolve around the female Kyuubi teaching Naruto about the secrets of the first chakra. This could lead to Naruto unlocking new powers and abilities that are different from his normal Sage Mode or other forms. Their relationship could also take on a romantic angle, with them growing closer as they train together and share their experiences.
One possible plotline could be about Naruto and the fem kyuubi fox form teaming up to fight a powerful new enemy. Maybe an ancient evil has been awakened and they have to combine their powers to defeat it. Another could be a story of the fem kyuubi fox form teaching Naruto more about his own chakra nature and how it relates to her power.
Well, it could start with the fem Kyuubi being in love with Naruto. Since she has negative feelings towards Kushina, she could begin by influencing Naruto's view of his mother. For example, she might show Naruto 'alternate' versions of Kushina's past actions that are not entirely true. As the story progresses, the fem Kyuubi could try to isolate Naruto from anything related to Kushina, like the Uzumaki clan heritage that Kushina represents. And perhaps, in the end, she realizes the error of her ways when Naruto discovers the truth about his mother. However, this is just one possible set of plotlines in such a complex and potentially controversial fanfiction concept.
Perhaps the story could revolve around the Fem Kyuubi teaching Naruto more about his Kitsune heritage. This could include special jutsu or abilities that only those with Kitsune blood can learn. The plot might also involve Naruto having to protect the Fem Kyuubi from other ninja who fear her power and want to seal her away again.
A plot could be that Fem Naruto and Fem Kyuubi have to go on a journey to find a special artifact. Along the way, they face various enemies and obstacles. They rely on each other's skills, with Naruto using her ninja techniques and Kyuubi her powerful chakra. This journey could also be a self - discovery for both of them, learning more about their true selves and their place in the world.
One possible interesting plotline could be the development of Naruto's relationships with the female Kyuubi and other female Bijuu. For example, how he overcomes the initial differences and misunderstandings between them. Maybe at first, the female Kyuubi is distrustful of Naruto due to her past experiences, but as they interact more, she starts to see his true nature and they form a bond.
Another theme is the emotional bond. The fanfictions usually show how their relationship evolves from a rather strange one (considering Naruto was once the host of the Kyuubi) to a deep emotional connection. There could be moments of trust - building, like Naruto learning to fully trust the fem Kyuubi with his life and the Kyuubi realizing Naruto's true value as a partner.