If we consider a Naruto - Danzo fight in a fanfiction, Naruto has several factors in his favor. His training with Jiraiya and other experiences have made him a formidable ninja. He can go into Sage Mode, which enhances his physical abilities and gives him access to more powerful jutsu. Danzo, while being a shrewd and experienced ninja, has his weaknesses. His over - reliance on the Sharingan and his somewhat underhanded methods might not be enough against Naruto's raw power and unwavering spirit.
A possible plot twist could be that Danzo reveals a hidden power related to the Sharingan that no one knew about. Maybe he can combine the powers of all the Sharingan he has in a unique way that gives him an edge over Naruto.
He'll likely lose his power and influence in the village. Once Naruto reveals his secrets, the villagers won't trust him anymore. His actions might be put on trial, and he could be exiled from the village.
Well, in some versions, Naruto might use his influence among the villagers. After Pain's attack, the village is in a state of rebuilding and re - evaluating. Naruto, being a hero, has the ears of the people. He could start by presenting evidence of Danzo's underhanded deals, like his connection to Orochimaru perhaps. Maybe he found some secret documents during the chaos that Pain caused, which link Danzo to unethical experiments or power - grabbing within the village.
One way Naruto could be like Danzo in fanfiction is through their view on secrecy. Danzo was big on keeping secrets and operating in the shadows. A fanfic could write Naruto into a scenario where he has to keep important information from his friends, believing it's for their protection, much like Danzo did. This would be a huge departure from his normal open and honest self.
A great fanfiction is 'Danzo's True Legacy in Root'. It portrays Danzo in a more sympathetic light. It tells the story of how Root was originally founded to protect the village from threats that the regular shinobi forces couldn't handle. And Naruto, through his own journey of understanding the darker side of the village, comes to realize that there was some good in what Danzo was trying to do, and he helps to reshape Root into a more positive force.
One possible motive could be to gain control over Naruto's power. Since Naruto has the Nine - Tails within him, Danzo might want to use that power for his own political or military gains. He's always been power - hungry and sees Naruto as a tool to achieve his goals of making Konoha stronger in his own way, which might involve more underhanded and controlling methods.
It could also be a completely new character introduced into the fanfiction. A foreign ninja who was inspired by some of Danzo's ideas (not the bad ones) and comes to Konoha to take on the role of successor, bringing in new perspectives and ways of doing things.
One possible fanfiction idea could be that Danzo is forced into an arranged marriage with a female ninja from a powerful clan. She initially despises him because of his ruthless reputation but gradually discovers his complex motives and they develop an unexpected bond.
It's popular because Danzo is a controversial character. He has done a lot of shady things in the Naruto series, like his role in the Uchiha massacre. Fans who dislike his actions create 'naruto danzo bashing fanfiction' to express their dissatisfaction.