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.
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 idea could be an OC Senju who has a unique ability related to plant manipulation, like being able to make plants grow rapidly into defensive or offensive structures. Another could be an OC Senju who is a healer and has to deal with the aftermath of a big battle in the Naruto world. Maybe an OC Senju who is on a quest to discover a long - lost Senju clan jutsu that was forgotten over time.
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 plot idea could be Tobirama's early days as a ninja. Explore his training, his relationship with his brother Hashirama, and how he developed his unique jutsu. Another could be a time - travel story where a modern - day Naruto character gets sent back in time and has to interact with Tobirama. Or perhaps a story where Tobirama has to deal with a powerful new enemy that challenges his beliefs and leadership.
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.
Another plot could involve the OC reincarnating into an existing character's body. This would lead to a lot of internal conflict as they try to adjust to the new identity while still having memories of their past self. They could also use their new position to change the course of events in the RWBY universe.
One idea could be that the OC is reincarnated as a member of a powerful but long - lost clan in the Naruto world. They then have to discover their clan's secrets and powers while also dealing with the ongoing conflicts in the shinobi world. For example, they might find a unique jutsu that was lost with their clan.
One idea could be Naruto time - travels back to Tobirama's era. He could use his modern - day knowledge and jutsu to help Tobirama in some great battles. Maybe Naruto teaches Tobirama about the concept of true friendship among different clans, which could change Tobirama's views on some policies he had for the clans.
In an oc reincarnation fanfiction, the OC might reincarnate into a world full of technology and advanced science. They might be the only one with memories of a more 'primitive' past life. This could lead to them using their knowledge of simpler times to bring a new perspective to the overly - technological society. For example, they could introduce more natural ways of living or thinking, which would be a contrast to the high - tech world they are now in. This could also create interesting conflicts as they try to convince others to consider their ideas.
One idea could be that the OC reincarnates into the RWBY world with some unique powers from their past life. These powers attract the attention of different characters, gradually forming a harem. For example, their power could be related to some ancient magic that is both feared and desired in the RWBY world.