One interesting 'Naruto Danzo Sensei' fanfiction could be about his early days as a ninja and how he developed his strict and secretive ways. It might explore his relationships with his peers at that time.
These fanfictions can also explore different time periods or alternate universes. For example, what if Danzo was the main sensei of Team 7 instead of Kakashi? This would completely change the story of Naruto, Sasuke, and Sakura. We could see how their characters would develop under his tutelage, and how the events of the Naruto universe would unfold in a very different way. It allows for a lot of creativity and speculation that adds fresh perspectives to the overall Naruto world.
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.
In the fanfiction, Naruto's new sensei could be a mysterious figure who has ties to the Sage of Six Paths. This person might have been waiting for the right time to appear and train Naruto. They could possess knowledge about the origin of chakra and how to fully unlock Naruto's power. It could also be someone who was once an enemy but has now changed their ways and wants to use their skills to train Naruto for the greater good of the ninja world.
There's a chance that Naruto's new sensei could be a self - taught ninja who has developed their own unorthodox style. This person sees Naruto's ability to think outside the box and wants to refine that in him. They could introduce Naruto to a new way of looking at chakra control and combat strategies that are completely different from what he has been taught so far.
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.
I think Orochimaru would be the most unexpected sensei. Usually, he's seen as a villain, but in a fanfiction, if he were to train Naruto, it would be extremely unexpected. He has a vast knowledge of jutsu, especially forbidden ones. He could teach Naruto some very powerful and unique abilities, but at the same time, Naruto would have to deal with Orochimaru's morally ambiguous nature.
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.