Well, the plot could revolve around a shinobi who has a special ability that is both a curse and a gift. During the Second Shinobi War, this shinobi is hunted by different factions because they believe his ability can be used to tip the scales of the war. However, the shinobi doesn't want to be a part of the war and is constantly on the run. In the end, he might be forced to use his ability to save a large number of people, including those from the villages that were hunting him, and in doing so, he changes the perception of his ability.
Well, perhaps Naruto could find himself in the middle of a crucial battle during the Second Shinobi War. He could befriend some of the young shinobi who later become important figures. He might help them out in a difficult situation, like rescuing a group of shinobi from an ambush. This would change the course of the war in small ways and also form strong bonds with those from the past.
One possible plot twist could be Naruto changing the outcome of a major battle. For example, in the Second Shinobi War, there were many crucial battles. Naruto might use his future knowledge to prevent the death of a key ninja. This would have a huge impact on the future of the ninja world as that ninja could then go on to change other events.
One interesting plot point could be Naruto's struggle with his new godlike powers. He might find it difficult to control them at first, causing some chaos on the battlefield. For example, he tries to heal a comrade but accidentally uses too much power and ends up giving them some sort of super - ability that they can't handle. Another plot point could be how the other shinobi react to his sudden transformation. Some might be in awe, while others might be jealous or even afraid.
He could meet the young Hiruzen Sarutobi. Naruto might learn a lot from him about the history and politics of the shinobi world at that time. They could also exchange jutsu knowledge to some extent.
It could be an original character. For example, a young ninja from a small, unassuming clan that has been overlooked in the grand scheme of the war. But as the war progresses, they show extraordinary skills and courage, becoming a key figure in the battles.
One idea could be focusing on a young, unknown shinobi who rises to prominence during the war. They might have a unique jutsu that catches everyone's attention.
In a Naruto 4th Shinobi War fanfiction, we could have a plot where the Akatsuki actually had a hidden agenda that was not related to the tailed beasts at all. They could be using the chaos of the war as a distraction to perform some other dark ritual. And perhaps a young shinobi discovers this and has to race against time to stop them while also fighting in the war.
One idea could be focusing on a young and inexperienced ninja who gets thrust into the chaos of the Third Shinobi War and has to quickly learn to survive. Maybe they form an unlikely alliance with a ninja from an enemy village because they both realize the senselessness of the war at a personal level.
One idea could be exploring the backstories of minor characters during the war. For example, how the normal shinobi were feeling and what they were doing on the sidelines. Another could be a what - if scenario where a different alliance was formed among the shinobi villages.
The fanfic could also focus on the personal lives of the characters. Naruto might finally have time to focus on his relationship with Hinata. There could be stories about how they build their family, and how Naruto balances his role as a family man with his duties as a hero of the ninja world. At the same time, other characters like Sasuke could also be exploring their new identities in a post - war world, trying to find their place and purpose.