A more complex plot could involve the 'knotting' as a way to merge their powers in a new and unexpected way. This new power attracts the attention of other villages or dark forces. Naruto and the female Kyuubi then have to navigate the political and dangerous situations that arise, all while exploring their relationship which is evolving due to the 'knotting'.
One plot idea could be that Naruto and Kyuubi have to work together to stop an ancient evil that is threatening the ninja world. This would require them to fully trust each other and combine their powers in new and unique ways.
One idea could be that the female Kyuubi beast, in her humanoid form, helps Naruto unlock a new level of his power. They go on a journey together to discover the secrets of an ancient jutsu that was lost long ago. This journey allows them to bond and Naruto starts to see the Kyuubi not just as a source of power but as a friend and ally.
One plot idea could be that Naruto, with the power of the Kyuubi, has to protect Hinata from a new and powerful enemy. This would show his growth as a shinobi and his love for Hinata. Another idea is that Hinata discovers a new way to help Naruto control the Kyuubi's power, strengthening their bond.
Maybe Naruto (futanari) discovers a new power within herself that is linked to the Kyuubi. As they explore this connection, they start to understand each other on a deeper level. For example, Naruto could use the Kyuubi's power in a more refined and unique way, changing the way battles are fought in the story. This could also lead to some interesting character development for both of them as they learn to trust and rely on each other more.
One plot idea could be Naruto, in his futa form, and the Kyuubi forming an unexpected bond. They might start to understand each other on a deeper level, like Naruto sharing his dreams of a united ninja world with the Kyuubi, and the Kyuubi revealing its own past traumas that led to its current state of being. Another idea is a story where they have to team up against a new, powerful enemy that is threatening both Naruto's world and the Kyuubi's existence. They could combine their powers in unique ways, with Naruto's futa abilities adding a different dimension to their combined strength.
One idea could be that the male Kyuubi helps Naruto unlock a new form of power. Since the Kyuubi has its own unique chakra, it could blend with Naruto's in an unexpected way, leading to a new and powerful jutsu. Another plot could involve the male Kyuubi teaching Naruto about the history of the tailed beasts from his perspective. This could give Naruto a deeper understanding of his own situation as a Jinchuriki.
Perhaps a plot where the female Kyuubi has to take on a human form to protect Naruto from a new, powerful enemy. In the process, they develop feelings for each other while fighting side by side.
Obviously, Naruto is one of the main characters. He is a well - known ninja from the Hidden Leaf village with a strong will and determination.
One plot idea could be that the Fem Kyuubi has a special connection with Naruto and Hinata. Maybe she can sense their deepening relationship and decides to use her power to protect them from an upcoming threat in the shinobi world. This could lead to a lot of action-packed scenes as they fight together against the common enemy.
One idea could be that the female Kyuubi helps Naruto gain unique powers. As part of the harem, she uses her fox - related abilities to protect Naruto from various threats. And Naruto, in turn, helps her understand human emotions better.