A member of the Uchiha clan would make a great main character. Maybe a young Uchiha who is against the more violent and power - hungry ways of some of the clan elders during the clan wars. He would have to struggle between his loyalty to his clan and his own sense of right and wrong.
A shinobi from a newly formed or very small clan could be the main character. This character would have to fight for their clan's survival during the clan wars. They would be at a disadvantage compared to the larger and more powerful clans, but through their wits and determination, they could make a name for their clan and change the course of the clan wars.
It could be a young Naruto Uzumaki, exploring his family's past during the clan wars era. He might discover secrets about the Uzumaki clan that have been long forgotten.
A good choice could be a young Itachi Uchiha. He was a prodigy even at a young age, and his story during the clan wars era could be really interesting. He was torn between his loyalty to the Uchiha clan and his understanding of the bigger picture in the village.
Naruto himself would be a great choice. He has a strong sense of justice and his time - traveling could lead to some interesting changes in the clan wars. He might try to end the wars early and bring peace among the clans. His unique abilities and personality would also make for an exciting story.
One idea could be focusing on a young shinobi from a minor clan who discovers a long - lost clan technique during the clan wars. This technique could give their clan an edge but also draw the attention of more powerful clans. Another could be a love story between shinobi from opposing clans, with their relationship being tested by the chaos of the clan wars.
It could also be a member of the village leadership who has a deep - seated prejudice against the Uchiha. This person is constantly trying to undermine the Uchiha's position and is willing to start and fuel the wars in order to get rid of them. They see the Uchiha as a threat to the stability of the village.
Naruto himself could be a main character, using his skills and influence to try and stop the clan wars. Another could be a young shinobi from a minor clan who has a special ability and wants to prove their clan's worth. And Sasuke could also be involved, perhaps having his own motives related to the clans.
One major theme is survival. The clans are in a fight for their existence. Some fanfics also explore the theme of redemption. A character from a war - causing clan may try to atone for their clan's actions and bring about peace. There are often complex family dynamics within the clans as well, which is another important aspect of these fanfics.
Well, it could change a lot. Maybe his birth becomes a symbol of hope in the midst of all the chaos. It might lead to different alliances being formed as clans see Naruto as a potential unifying factor.
A great plot idea could be to explore the role of the Hyuga clan in the clan wars era. Maybe there was a power struggle within the clan regarding their stance in the wars. Or, you could write about a forbidden love story between a member of the Uchiha clan and a member of an opposing clan during this time. This would add a lot of drama and conflict to the fanfiction.
Naruto could be more cautious. In the clan wars setting, danger is everywhere. So, he would learn to be more careful about who he trusts. Also, his determination to bring peace might be even stronger. Since he was born into the chaos of war, he would have a deeper understanding of how bad it is and strive harder to end it. For instance, he might start training at a younger age to protect himself and others from the ongoing wars.
Obviously, Naruto is one of the main characters. He is usually at the center of the story, using his skills and determination to navigate the clan wars. Sasuke is also often a main character, as his past and connection to the Uchiha clan play a big role. Sakura might be there too, using her medical ninjutsu to help those injured in the wars. And then there are the clan leaders, like the Nara clan leader or the Hyuga clan leader, who have their own agendas and power dynamics within the story.