In fanfiction, a great way to develop their relationship is through shared goals. For example, if there is a threat to the ninja world that both Naruto and Female Zetsu want to stop. Working together towards this goal, they will have to communicate, trust each other, and gradually their relationship will grow. They could learn from each other's strengths and weaknesses, like Naruto's determination inspiring Female Zetsu and Female Zetsu's unique knowledge of certain things helping Naruto.
A more complex way to develop their relationship could be through conflict first. Maybe Female Zetsu initially has some goals that conflict with Naruto's. But as the story progresses, they come to understand each other better. For instance, Female Zetsu might be trying to protect a certain part of the forest which Naruto unknowingly endangers while on a mission. Through resolving this conflict, they start to see the good in each other and form a bond that could be further explored in the fanfiction.
The relationship can start with mutual curiosity. Naruto is always open to new things and people, and Female Zetsu is a mysterious being. So, Naruto might be intrigued by her and start to interact with her more, which begins their relationship development.
The relationship can start with mutual respect. For example, if female Naruto shows great courage in a battle, Minato, who values bravery, will start to notice her. Then they can have small interactions like sharing their thoughts on ninja philosophy which will bring them closer.
The relationship can start with mutual suspicion. For example, Naruto initially thinks the female Akatsuki member is just another evil foe. But as they interact more, he realizes she has her own reasons for being in the Akatsuki. This realization can be the first step in developing a more complex relationship.
To develop their relationship in fanfiction, one approach could be to give the female Kurama a backstory that makes her more relatable to Naruto. Say she was once a normal fox in the forest before being transformed into a powerful being. Naruto, with his kind heart, would be sympathetic to her situation. They could also have moments of cultural exchange. Naruto could teach her about human traditions, and she could share with him the ancient knowledge of the fox spirits. This exchange of ideas and experiences would help build a strong relationship between them. Moreover, having them face internal conflicts together, like Naruto's struggle with his own power and the female Kurama's identity crisis, would also strengthen their bond as they support each other through these tough times.
The relationship can be developed through shared battles. When they fight side by side against foes, they can start to trust each other more. For instance, if they face a powerful enemy that neither could defeat alone, they would rely on each other's strengths.
They could start training together more often. Through intense training sessions, they would grow closer as they learn from each other's strengths and weaknesses.
In the fanfiction, the relationship might develop through a series of challenges. For example, Naruto might need to rescue female Orochimaru from a situation where her own past actions have caught up with her. This act of selfless heroism on Naruto's part would make Orochimaru re - evaluate her view of him. She would start to see him as someone different from the other shinobi she has known. As they spend more time together, they would start to understand each other's motives and dreams, leading to a deeper relationship.
Another way is through a prophecy. In the fanfiction, there could be a prophecy that only Naruto and female Madara together can save the shinobi world from a great disaster. At first, they don't believe it, but as the signs of the disaster start to appear, they are forced to work together. As they spend time together trying to prevent the disaster, they learn about each other's pasts, hopes, and dreams, which leads to a deep emotional connection.
The relationship can be developed through shared missions. When they are on a mission together, they can rely on each other's skills and learn from one another. For example, Naruto's vast combat experience can help Sarada in tough battles, and Sarada's fresh perspective can give Naruto new ideas.
In fanfiction, their relationship can be developed through shared experiences. For example, they could be trapped in a mysterious dimension together. During their time there, they have to rely on each other to survive, which makes them trust one another more.
Another way is through cultural exchanges. Naruto could introduce the Mizukage to some of the unique traditions of the Hidden Leaf, like the Ninja Academy system or the annual Chunin Exams. In return, the Mizukage could share the secrets of the Hidden Mist's special jutsu training. This mutual exchange of knowledge and experiences would bring them closer.