A common theme is the relationship development between the sub female Kyuubi and Naruto. It often involves the exploration of their unique bond, perhaps starting from a place of misunderstanding and growing into something deeper.
One common theme is power. Since Kyuubi is a powerful entity, fanfictions often explore how Naruto's relationship with Kyuubi affects his power growth. Another theme is friendship or a deeper bond. Given that Naruto has a unique connection with Kyuubi, stories might focus on how they come to understand and trust each other more over time.
One common theme is the exploration of their combined powers. Since Naruto has the power of the Kyuubi and Moka has her own unique vampire abilities, stories might focus on how they use their powers in battles or to protect each other.
One common theme is the power of friendship. Naruto and the fem Kyuubi often start as adversaries but gradually become friends and support each other. Another theme is self - discovery. Naruto discovers new aspects of himself through his relationship with the fem Kyuubi.
Power and control are often themes. The female Kyuubi has great power, and Naruto has his own power and his experience with the original Kyuubi. So, in fanfiction, there could be a struggle or a cooperation regarding who has control over what. Also, the theme of acceptance. Naruto has to accept this new form of the Kyuubi, and the Kyuubi might have to accept Naruto's way of doing things.
One common theme is power. Since Naruto is a demon and Kyuubi is a powerful being as well, the stories often revolve around how they use and control their powers. Another theme is partnership, showing how they work together.
Another theme is the exploration of a unique relationship. Since it's a crossover, the relationship between Naruto and the fem Kyuubi is different from the original Naruto - Kyuubi dynamic. It can range from a mentor - mentee type to a more equal partnership, and fanfics often explore how this relationship develops over time. There are also a lot of emotional exchanges, like trust - building and mutual understanding. For instance, in some stories, Naruto has to earn the fem Kyuubi's trust, and this process is full of challenges and revelations.
Well, a frequent theme is the exploration of identity. Naruto's identity as a jinchuriki and the fem - Kyuubi's own nature are often delved into. Also, redemption can be a theme. Maybe the fem - Kyuubi has some past actions she wants to make up for, and Naruto is involved in that process. And of course, love and companionship are common, showing how they support and care for each other in different situations, which could range from battles to more peaceful times in the Hidden Leaf Village.
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.
One common theme is the transformation of their relationship. It usually starts with Naruto having a more adversarial or at least a complex relationship with the Kyuubi due to its power, but as the female aspect is introduced, it turns into a love story. Another theme is acceptance. Naruto has to accept this new form of the Kyuubi and his feelings for her, and she has to accept his world and the fact that she's now in a different kind of relationship with him.
Common themes include the idea of transformation. Naruto's life is transformed when he enters into this relationship with the fem Kyuubi and her harem. His world view changes, and so does his approach to life. Another common theme is the sense of community within the harem. The members of the harem support each other and Naruto, creating a unique community. This is different from the normal Naruto world where he is often more alone. Also, the theme of mystery is sometimes present. There are often secrets about the fem Kyuubi and her past that Naruto has to uncover as he gets closer to her and the other harem members.