One common theme is the idea of opposites attract. Female Tsuna is often depicted as kind and gentle while Xanxus is tough and brash. Their differences draw them together in these stories.
Redemption is also a theme sometimes. Xanxus has a rather dark past in the original story. In some 'female Tsuna x Xanxus' fanfictions, female Tsuna becomes a source of light for Xanxus, guiding him towards a path of redemption. This gives the story a deeper emotional layer and makes the relationship between the two characters more complex and interesting.
One common theme is the idea of redemption. Xanxus is often portrayed as a rather rough character, and in these fanfictions, he might find a way to redeem himself through his interactions with Tsuna.
Another good one is 'Tsuna and Xanxus: Unlikely Bond'. In this fanfiction, the author explores how a female Tsuna might break through Xanxus's tough exterior. It has a lot of emotional moments and the way the two characters' personalities clash and then come together is really engaging.
One common theme is the struggle between her assassin identity and her personal life. For example, she might have to keep her assassin activities a secret from her friends and family. Another theme is the development of her assassin skills. This could involve training sequences or her learning new and unique assassination techniques. Also, there's often the theme of redemption or a moral struggle. Even though she's an assassin, she may question the morality of her actions.
Maybe in the fanfic, Xanxus raises the female Tsuna in a world where the Vongola family is facing a new and unknown threat. Xanxus, with his rough and tough attitude, has to soften a bit to be a proper guardian for her. He might teach her combat skills as well as the politics within the mafia world, and she could in turn change his perspective on certain things.
Power - up or growth themes are seen too. As both characters have their own power - related storylines in their original series, in the fanfiction, they might combine their powers or help each other grow stronger, which makes for an interesting narrative.
One common theme is growth. Female Tsuna often has to grow as a person, and Reborn is there to guide her. For instance, she might learn new skills or gain more confidence. Another theme is friendship. Even though there can be romantic undertones, their friendship is a central part of the story. They rely on each other and trust each other.
A common theme is the exploration of a romantic relationship. Given their different personalities in the original series, seeing how they interact in a romantic context is interesting. Another theme could be the growth of the characters. For instance, how a female Tsuna might become more confident or assertive in the presence of Hibari, and how Hibari might become more open - minded.
Their relationship might start off rocky. Xanxus is a tough character, and the female Tsuna would probably be a bit intimidated at first. But as he teaches her and protects her, she would start to see his good side. They could develop a father - daughter - like relationship, where Xanxus is the strict but caring father figure.
In this fanfiction, it could start with Tsuna getting lost in a part of the Vongola headquarters where Xanxus usually lurks. Xanxus, known for his short temper, is about to attack Tsuna when he notices something in Tsuna's eyes - a kind of hidden strength. Tsuna, not fully understanding the danger, just stands there. This moment of hesitation from Xanxus gives Tsuna a chance to speak. They start a conversation that is filled with underlying threats from Xanxus and nervous stutters from Tsuna. But as they talk, they both start to see that there is more to each other than what they initially thought. This encounter could be the start of a strange and complex relationship within the Vongola family.
One common theme is friendship turned into love. Since they are likely friends in the original story, fanfiction often explores how that relationship deepens into romantic love.