One common theme is the power dynamic between them. Since Reborn is Tsuna's mentor in the original series, this often plays into their relationship in the fanfiction. There's also the theme of Tsuna's growth, not just as a mafia leader but also in his relationship with Reborn.
Another theme is the secrecy and the forbidden nature of their relationship. Given the context of the series and their different positions, a lot of fanfictions explore how they navigate their feelings while keeping it hidden from others. It adds an element of drama and tension to the stories.
The theme of protection is also quite common. Reborn is a powerful hitman, and Tsuna is the future mafia boss. So, Reborn protecting Tsuna, and in some cases Tsuna protecting Reborn in his own way, is often explored in these fanfictions. This shows the depth of their bond and care for each other.
Power dynamics is often a theme. Dino being more experienced or having more power in some aspects, and Tsuna growing into his own power. This power play can be an interesting aspect in their relationship in the fanfiction. Also, loyalty and trust between them is a big theme. As they face various challenges together, their loyalty to each other is tested and strengthened, which is often explored in these stories.
One common theme is the idea of redemption. Mukuro often has a dark past, and through his relationship with Tsuna, there's a sense of him finding a path to redemption. Another theme is the power of friendship and love. Their relationship is often portrayed as something that can overcome many obstacles.
The theme of friendship is also prevalent. Their relationship evolves from a teacher - student dynamic to a deep friendship. They support each other through various challenges, like in 'The Bond of Reborn and Tsuna' where they go through many trials together and their friendship becomes unbreakable.
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.
Overcoming challenges together is also a frequent theme. Since they are often in difficult situations in the original story, in the yaoi fanfictions, they might face challenges that test their relationship, such as rivalries or threats from other characters. And through these, their bond deepens. For example, they could be facing a new enemy in the underworld who is trying to break them apart, but they hold on to each other and come out stronger.
Friendship turning into love is a very popular theme. Tsuna and Kyoko usually start with a platonic relationship. As the story progresses, they start to see each other in a new light. Also, the theme of loyalty is there. Tsuna's loyalty to his friends and family extends to his relationship with Kyoko, and vice versa.
Another theme is the power of friendship and family. Since they are part of the Vongola family in different eras, their relationship is often centered around the idea of family loyalty and how they support each other. They might also make friends along the way who play important roles in their adventures.
The theme of friendship also pops up a lot. Despite their different personalities and roles, their bond as friends is a popular aspect to write about. Additionally, some fanfictions might focus on the power - up of Tsuna with Reborn's training, showing how he overcomes his weaknesses and becomes more powerful in the story.
One common theme could be growth. With the 'child reborn' aspect, there's often a journey of the character growing and changing, especially with Tsuna as a tutor figure guiding them. Another theme might be the exploration of different relationships. Tsuna's role as a tutor can lead to various types of relationships, like a mentor - mentee relationship or something more complex.
In many of these fanfics, a common theme is the transformation of Fem Tsuna. It could be her physical transformation as she grows more confident in her femininity, or her mental transformation as she becomes more powerful and assertive. Some fanfics also explore the idea of alternate universes, where the rules of the Katekyo Hitman Reborn! world are slightly different. This allows for different takes on the Reborn x Fem Tsuna relationship, such as them being from rival families or having different abilities.