Another interesting aspect could be the OC's struggle with adapting to Sasuke's personality and the expectations placed on him. They have to balance between being true to their own self and fulfilling the role of Sasuke. This internal conflict could create a lot of drama and character development, especially when dealing with characters like Itachi and the Uchiha clan's legacy.
Maybe the OC reborn as Sasuke has some special powers from their previous life that they combine with Sasuke's natural abilities. This could lead to new and exciting jutsu creations. They could also use their knowledge of future events to help Sasuke form better relationships with his teammates, like Naruto and Sakura, which would in turn affect the overall story arc of Naruto.
One idea could be to give the OC a new power or ability in their reborn state. For example, if it's a fantasy setting, they could gain the power to control an element they were previously weak against. Another idea is to change their personality slightly due to their rebirth experience, like becoming more confident or cautious. You could also explore a different backstory for the OC in the fanfiction, perhaps one that was hidden before their rebirth.
Also, the oc might have different goals than Issei. While Issei is often focused on his perverted desires as well as becoming stronger to protect his friends, the oc could have a more noble or self - centered goal like finding a way back to their original world or using the power in this new world for personal gain in a non - perverted way. This contrast in motives can create a lot of tension and interesting plot developments.
One plot idea could be the reborn character having all of Sasuke's memories from the start. This would allow them to quickly adapt and perhaps change some of the events that Sasuke went through in the original story. For example, they could avoid some of the more tragic moments or make different choices regarding his relationships.
Well, perhaps the OC reborn as Kurama tries to find a way to coexist peacefully with the jinchuriki in a different way than in the original story. They could use their unique perspective to broker better relationships between the tailed beasts and the humans. Maybe they also try to uncover secrets about the origin of the tailed beasts that were previously unknown.
One idea could be an OC who has a special power related to time manipulation in the 'hitman reborn' universe. They could use this power to change the outcome of battles or prevent certain tragedies. Another could be an OC that is a long - lost relative of one of the main characters and has a different view on the mafia world, causing some internal conflicts.
One idea could be that the OC, reborn as Naruto, uses their prior knowledge to quickly master jutsu. For example, they might know about the Rasengan from the start and be able to perfect it faster. Another plot could involve the OC changing the relationships in the village. Maybe they befriend Sasuke earlier and prevent his defection. Or they could introduce new ninja techniques from their past life to the Hidden Leaf.
Another plot could involve an OC reborn into the body of a criminal in the Naruto world. They have to struggle to redeem themselves and prove that they are not the same person as the original criminal. Along the way, they could discover the real reasons behind the original criminal's actions and try to right the wrongs that were committed.
One idea could be that the reborn OC genius uses their extraordinary intelligence to solve a mystery that has baffled the entire community. For example, they might figure out the secrets behind an ancient artifact's power.
One idea could be that the OC, now as Kakashi, has to deal with the same traumas Kakashi had but with a different perspective from their original self. For example, they might handle the loss of their comrades in a new way that changes the course of events in the Naruto world.
A really interesting plot would be Naruto, reborn as Sasuke, trying to prevent the events that led to Sasuke's departure from Konoha in the first place. He would use his knowledge of the future and his Naruto - esque determination. He might also struggle with Sasuke's memories and emotions, which could create internal conflict. For example, when dealing with Orochimaru, he would have to fight the urge to follow Sasuke's original path while also trying to outwit Orochimaru with his own Naruto - like wits.