Character development could be complex. The OC would be influenced by Madara's ideology at first. But as they interact with other characters in the Naruto universe, like Naruto or Sasuke, they start to question Madara's ways. This would lead to a transformation in the OC's beliefs and personality. They might become more empathetic towards others and less focused solely on power, which was Madara's main pursuit.
The OC would likely start as a relatively inexperienced ninja. Under Madara's tutelage, they would become more confident and skilled. For example, they might learn how to better control their chakra.
One possible plot is that the OC, as Madara's student, gets involved in the Uchiha clan's affairs. The OC could be in a position where they have to choose between loyalty to Madara and what they believe is right for the clan. This internal conflict could drive the story forward as the OC tries to navigate the complex politics and power plays within the Uchiha.
One possible fanfiction could be about Madara as a student in the ninja academy. He might be a prodigy from the start, showing extraordinary skills in combat and jutsu. His arrogance as a young student could also be a major part of the story, as he looks down on his peers but at the same time, secretly admires some of their unique abilities. This could lead to some interesting rivalries and friendships within the academy.
Fem Naruto's character development could also involve her learning from Madara's mistakes. Madara's past actions led to a lot of destruction. Fem Naruto, seeing this, could vow to take a different path. This would require her to grow in wisdom and restraint. On the other hand, Madara could develop by seeing Fem Naruto's potential. He might start to believe in a better future for the ninja world through her, which would be a huge shift in his character from his more nihilistic views in the original story.
In this fanfiction, Naruto's character development could be seen as a counterpoint to Madara's. Naruto is all about hope, friendship, and protecting the village. Madara has been through a lot of pain and betrayal which led him to a path of destruction. If Naruto is like Madara in this fanfiction, his development might involve a struggle between his own beliefs and the allure of Madara - like power and ruthlessness. However, Naruto would probably still find a way to use any new - found power in a more benevolent way compared to Madara.
Naruto might become more conflicted. Since Madara had some extreme views, Naruto would have to grapple with those ideas. He could become more secretive as he tries to understand Madara's motives better without alarming his friends. For instance, he might start training alone more often to study Madara - inspired techniques.
The character could start off with all of Madara's arrogance and then gradually learn humility as he experiences new things in his reincarnated form. For example, if he is reincarnated into a weak body, he has to rely on others at first, which is a new concept for him.
The student could be from a different village or clan and is sent undercover to learn from Madara. As the student gets closer to Madara, they start to understand his motives and the true nature of power in the ninja world. They might then have to decide whether to betray their own village or side with Madara, leading to a complex web of relationships and plot twists.
It could be another powerful ninja who sees the student as a threat to their own power or plans. Maybe someone who doesn't want Madara to pass on his knowledge to an outsider or a young upstart.
One idea could be to make the OC a healer. Since Naruto often gets into dangerous battles, a mother - like OC who can heal his wounds would add an interesting dynamic. The OC could have learned healing jutsu from a hidden clan. Another idea is to give the OC a tragic backstory, like losing her family in the war, which makes her protective of Naruto as she sees in him the hope for a better future.
The plot could revolve around Madara being an outcast among the students. Despite his great power, his ideas and his way of thinking might be too radical for the others. He could be trying to form his own group within the academy, with like - minded students who believe in his vision of a stronger ninja world. This would create a lot of conflict with the established order in the academy.