It could be an original character created specifically for the fanfic. This character could be a young ninja with a unique power or backstory, like a shinobi who has the ability to control plants in combat.
Sasuke could also be the main character. His quest for power and revenge could be further explored in the context of the war. He might find himself in situations where he has to choose between his personal goals and the greater good of his village and the shinobi world.
He might change the course of many battles. For example, he could use his Rasengan to take out powerful enemies quickly. His ability to inspire others would also boost the morale of the shinobi on his side.
One idea could be to focus on a young, unknown shinobi who rises to prominence during the war. Maybe they discover a new jutsu that changes the tide of a crucial battle.
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.
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.
In a fanfiction scenario where Naruto starts the 4th Shinobi War, it would completely change the whole Naruto universe's narrative. Naruto is known for his desire for peace, so if he starts the war, it might be due to some extreme manipulation or a misunderstanding of the situation. For example, he could be tricked by an enemy who has disguised themselves as an ally and convinced Naruto that starting the war is the only way to protect the Leaf Village. This would lead to a situation where all his friends and comrades would be forced to either oppose him or be dragged into a war they didn't want.
In some fanfictions, if Naruto was sent to the Third Shinobi War, he could change the course of many battles. His unique jutsus like the Rasengan might surprise the enemies. He could also inspire his comrades with his never - give - up attitude.
First, you need to do research on both universes. Know the rules of magic in Harry Potter and the abilities and politics in the shinobi world. Then, come up with a unique plot that ties the two together. For example, a dark force could be threatening both worlds. Decide on which characters from each side will be the main protagonists and antagonists.