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.
I'm not sure of specific titles off the top of my head. But you could try joining some Reborn! and KHR (Katekyo Hitman Reborn) fan communities on social media platforms like Tumblr or Discord. Fans there are often very helpful in sharing their favorite fanfictions, including those with a Reborn x Tsuna Yaoi theme.
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 popular Gokudera x Tsuna yaoi fanfiction is 'The Unspoken Bond'. It delves deep into their relationship, exploring the unspoken feelings between them. The author does a great job of portraying their personalities in a way that makes their relationship development seem natural within the context of the story.
Well, for one, the characters are already well - loved from the original source. Fans like to explore different relationship possibilities for them. And the yaoi aspect adds a layer of forbidden or secretive love, which is often very alluring. The idea of Gokudera and Tsuna having a romantic relationship that they might have to hide or struggle with due to various reasons in the story world is a big draw for many fans of this type of fanfiction.
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.
There are quite a few. You can start by looking on popular fanfiction platforms. Some might focus on their unique relationship dynamics, like how they support each other in the face of challenges. However, the quality can vary a great deal.
The contrast between their characters. Enma might have certain traits that Tsuna doesn't and vice versa. This difference creates a dynamic that is fun to explore in a yaoi relationship.
Finding dino x tsuna yaoi fanfiction can be a bit tricky. You could also check out some fanfiction forums where fans discuss and share their favorite works. Sometimes, fellow fans can point you in the right direction. Another option is to look for dedicated KHR (Katekyo Hitman Reborn, assuming that's where Dino and Tsuna are from) fanfiction communities. They may have a collection of such stories.
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.