A civilian who somehow gets involved in the war and discovers they have latent shinobi abilities. They could start as a clumsy and inexperienced character but grow into a powerful force.
'The Unseen Hero of the 4th War' is a great one. It focuses on a character who is often overlooked in the original story but plays a crucial role in the fanfiction. The writing style is engaging and it really dives deep into the character's emotions during the chaos of the war.
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.
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.
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.
One idea could be focusing on a young shinobi who is an unknown hero during the war. They might use some unique and forgotten jutsu to turn the tide in crucial battles.
I think the 'Fourth Shinobi War Novelization Fanfiction' might focus on exploring the characters' inner thoughts during the war. For example, it could show Naruto's determination in more detail, how he was feeling while facing such a huge threat.
A third idea is a story centered around a shinobi who was thought to be dead but actually survived and is now trying to get back to the battlefield. Along the way, they discover secrets about the origin of the war or new jutsu that could turn the tide of the battle. They have to overcome their own physical and mental weaknesses while also evading the enemy who believes them to be dead.