Yes, there are likely some out there. Fanfiction platforms are filled with all sorts of creative and unique ideas. You can try searching on major fanfiction sites like Archive of Our Own or FanFiction.net.
The plot could involve Harry gradually realizing his past life as Tobirama. He might start having strange dreams or visions. As he discovers his reincarnation, he could use Tobirama's ninja - like strategies in the wizarding world. For instance, his ability to plan and execute complex maneuvers could give him an edge against Voldemort. Also, he could introduce some of Tobirama's ideas about leadership and community building to Hogwarts, changing the way the school is run.
In fanfiction, anything is possible. So, Naruto could be Tobirama's reincarnation. Some fanfic authors like to play with the idea of reincarnation to bring new elements to the story. They might make Naruto inherit some of Tobirama's chakra nature or jutsu. This can create unique scenarios where Naruto has to deal with the memories or expectations that come with being Tobirama's reincarnation. It can also change the dynamics between Naruto and other characters, like Sasuke, as they might view Naruto differently if he has such a connection to an important figure from the past.
Well, it depends on what you consider 'good'. Some people might like ones that focus on Tobirama's reincarnation's impact on the existing Naruto world politics. For example, there could be a story where the reincarnation has to deal with the power struggles between the different ninja villages in a new and interesting way. Others might prefer more character - driven stories that explore Tobirama's relationships with the other characters in his new life. You really have to dig through the available fanfictions to find the one that suits your taste.
One implication could be a change in Naruto's abilities. He might gain some of Tobirama's water - based jutsu or his talent for creating complex ninja techniques. Another is in his relationships. The village elders might treat him differently, perhaps with more respect or suspicion depending on their views of Tobirama.
Well, identity is a big theme. The reincarnation has to figure out who they are in relation to Tobirama. Are they a complete reincarnation with all of Tobirama's memories and skills? Or are they a new person with just a connection to Tobirama? Also, there's often the theme of redemption. Maybe Tobirama had some regrets in his past life, and the reincarnation has the chance to make things right. And of course, the theme of friendship and alliances, as the reincarnation has to interact with the existing characters in the Naruto universe and form relationships with them.
One way is through their relationships. Tobirama had his own set of comrades and rivals. The OC could form different kinds of relationships. They could befriend outcasts that Tobirama might not have associated with. Also, the OC's reaction to modern technology or new ninja techniques could be different. Maybe Tobirama was traditional, but the OC is eager to adapt and combine old and new. The OC could also have a different sense of humor, which would show in their interactions with others.
One interesting plot twist could be that Naruto starts to have memories of Tobirama's past battles. This would make him question his own identity and purpose. Another could be that Tobirama's reincarnation in Naruto causes a shift in the power dynamics among the villages. It might make other villages see Konoha as a greater threat or as a source of new knowledge.
For Naruto's friends like Shikamaru and Choji, they would be quite surprised. Naruto might start to act more like Tobirama in some ways, which could be a bit off - putting at first. He could be more strict or more focused on the long - term goals of the village. This might cause some friction in their friendships until they understand what's going on. With the elders of the village, Naruto could gain more respect as Tobirama was a highly respected figure. But it could also make some of them wary, as they might fear Naruto using Tobirama's knowledge in ways they don't like.
One idea could be that the OC has Tobirama's memories slowly resurfacing. As they do, the OC starts to show extraordinary skills in water jutsu, just like Tobirama was known for. Another plot could involve the OC being drawn to the Senju clan's old haunts and trying to piece together Tobirama's past, which leads to uncovering long - lost secrets of the clan.