A plot where Reborn and Tsuna are stuck in an alternate dimension that is a mix of their worst nightmares. They have to work together to find a way out, and in the process, they discover new things about each other and their relationship deepens. Tsuna might have to overcome his insecurities in a more extreme environment, while Reborn shows his more vulnerable side.
One idea could be a time - travel plot where Tsuna is sent back in time and has to rely on Reborn's teachings from the start again, but with the knowledge he already has. This would lead to some really different interactions and a chance to change certain events in a more strategic way.
Another plot could be Tsuna traveling back to a time when his father was still around. He could get to know his father better and learn some hidden family secrets. This would not only strengthen their relationship but also give Tsuna an edge in his future as the Vongola boss. He might learn about some special powers or techniques that his father knew but never got to pass on to him in the original timeline.
One interesting plot could be Naruto using his ninja skills in the world of Tsuna. For example, he might use his shadow clone jutsu to help Tsuna deal with multiple threats at once. Another could be Naruto teaching Tsuna some of his unique chakra control techniques which could enhance Tsuna's own combat abilities in his world.
One idea could be that the OC is a new transfer student to the school where the characters of Khr Reborn are. They have a special ability that catches Reborn's attention, like being able to sense danger before it happens. This could lead to them being drawn into the dangerous and exciting world of the series.
One idea could be a story where the OC is a new student at Tsuna's school. They initially clash due to misunderstandings, but as they get to know each other, they start to develop feelings. For example, the OC could be very outspoken and Tsuna is shy at first, but her boldness helps him come out of his shell.
Well, perhaps in this fanfiction, Harry, now Tsuna, has visions of his past life at Hogwarts during his battles in the KHR world. These visions give him an edge as he can draw on the spells and strategies he used against Voldemort to fight his new enemies. Also, his relationship with Reborn could be really interesting. Reborn might be intrigued by Tsuna's strange bursts of knowledge and skills that seem to come out of nowhere, which are actually remnants of Harry's past magical training.
One idea could be that the main character discovers a hidden power within themselves while in the world of 'khr' and this new power is somehow related to love. Maybe it helps them to form stronger bonds with the other characters and overcome a great evil together.
In KHR Tsuna x Hibari fanfiction, the settings can play a huge role. For example, if it's set in the school environment of Namimori, their interactions would be shaped by the school rules and the presence of other characters. Some fanfictions might explore how their relationship evolves when they face a common enemy, like the Vongola enemies. This can bring out different sides of their personalities and how they support each other in tough situations.
Often, they focus on the unique bond between Tsuna and Chrome. It can be a deep friendship or something more romantic. The stories usually incorporate elements from the original work, like the mafia world setting and their special powers.
With Reborn, you can develop his past. Maybe write a story where we learn more about his training and how he became the world - class hitman. This could add more depth to his character and also show how his past experiences influence his relationship with Tsuna. For example, if he had a difficult master - apprentice relationship in the past, it could make his bond with Tsuna even more special.
The theme of friendship - turned - more - than - friendship is also quite common in KHR Tsuna x Hibari fanfiction. They start as schoolmates or comrades in the Vongola family battles. As they spend more time together, feelings may develop that go beyond simple friendship. And of course, the theme of redemption can be there too. If one of them makes a mistake or has a dark past, the other can be a source of support and redemption.