Definitely the moment when Naruto takes his last breath. Imagine him on the battlefield, surrounded by his friends or at least in a place where he has fought bravely. His last words, if any, about his dreams for peace and how he wishes his friends would carry on without him. And then his body going limp. His friends trying to revive him but failing. It's a scene that would be both tragic and would stay with the readers for a long time.
A really heartbreaking scene could be the reaction of Naruto's teachers. Kakashi, who has seen Naruto grow from a troublemaking kid to a hero, would be devastated. He might blame himself for not being able to protect Naruto. And Iruka, who was like a father figure to Naruto in the beginning, would be inconsolable. Just seeing their faces filled with grief as they look at Naruto's lifeless body would be enough to make any reader's heart ache.
One of the most heartbreaking scenes could be when his friends find out about Naruto's death. For example, Sakura, who has been with Naruto through so much, would be completely shattered. Her reaction of disbelief and then overwhelming grief would be really sad. Another scene might be when the whole village of Konoha hears the news. The silence that would fall over the village, with people just stopping in their tracks, would be a very poignant moment.
If Naruto dies in the Fourth Shinobi War in fanfiction, it would have a huge impact. For one, the morale of the Allied Shinobi Forces would plummet. Naruto was the symbol of hope. Without him, many might lose the will to fight. His friends like Sasuke would be deeply affected. Sasuke's whole journey of redemption was somewhat tied to Naruto. His death could also lead to a power vacuum. Nations that were relying on Naruto's strength and his idea of peace might fall into chaos as they scramble for power or new forms of protection.
In a 'godlike Naruto' Fourth Shinobi War fanfiction, Naruto could have a connection to a divine entity. Maybe he discovers he is a descendant of a god of the ninja world. This newfound heritage gives him superhuman strength, speed, and the power to foresee his opponents' moves. He uses these powers to single - handedly take on Madara Uchiha and Kaguya. His godlike status also earns him the respect and loyalty of all the shinobi clans, uniting them under his leadership against the common enemy.
I think Obito could be really interesting. His complex backstory and his role in the war were so crucial. You could explore his internal struggle further, like his lingering feelings for Rin and how that influenced his actions during the war in more depth.
Definitely when Naruto can no longer perform his signature Rasengan. He tries so hard but his body just won't allow it. His friends are there, watching helplessly. Also, the moment when he has a final conversation with Iruka - sensei, reminiscing about the old days when Iruka was the first to believe in him. It's a connection to his past that is being severed by the illness, which is very poignant.
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.
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.
Naruto himself could be a likely time - traveler. He has a strong sense of justice and a desire to protect his friends and the village. If he saw a way to go back in time and prevent the destruction and loss in the Fourth Shinobi War, he would probably take it. Plus, his chakra and determination might be what enables the time - travel in the first place.
In some fanfictions, a heartbreaking scene might be when Hiccup sacrifices himself to save Astrid from a powerful enemy. He might push her out of harm's way just as a deadly attack is about to land on her, and then he takes the full brunt of it. The moment when Astrid realizes what he's done and rushes to his side, crying and begging him not to leave, would be extremely sad.
One popular original character might be a young, prodigious shinobi from a small village. They have unique abilities that set them apart, like the power to control the elements in a completely new way. Another could be a mysterious figure who shows up during the war and has a connection to an ancient shinobi clan that was thought to be extinct. And then there's the brave female shinobi who defies gender norms and becomes a respected leader on the battlefield.
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.