In a Naruto fanfic, some S - rank ninjas that Naruto might banish could be those from other villages who pose a great threat. For example, the Raikage's brother, Killer Bee, if he were to be brainwashed and start attacking the Hidden Leaf. Naruto would have to banish him to protect his village. Also, the Mizukage could be a character that Naruto banishes if she were to be corrupted by some evil force and start oppressing her own people and threatening other villages. And then there are the ancient S - rank ninjas that might be resurrected in the fanfic and cause trouble, like Hashirama's rival, Madara's brother, Izuna. If he were to be brought back and be a threat, Naruto would banish him.
Well, in a fanfic scenario, Kabuto could be an S - rank ninja that Naruto banishes. After all, Kabuto has a lot of power and knowledge, and if he were to use it for evil again, Naruto would have no choice. Also, Nagato could be another candidate. If Nagato were to regain his old beliefs and start attacking villages again, Naruto might banish him to stop the cycle of violence. And of course, there's Obito. If Obito didn't have his change of heart in the fanfic and continued to be a threat, Naruto would surely consider banishing him.
One possible plotline could be that Naruto discovers a group of S - rank ninjas who are secretly plotting against the Hidden Leaf Village. He decides to banish them to protect the village. Another plotline might involve Naruto being forced to banish an S - rank ninja who has committed a heinous crime but has some sort of connection to him. Maybe it's an old friend turned bad. And a third plotline could be that Naruto banishes S - rank ninjas from other villages who have invaded the Hidden Leaf and are too powerful to be kept as prisoners.
It could also be due to Naruto's outcast status in the village initially. Danzo might think that banishing Naruto would be an easy decision as Naruto doesn't have many supporters at first. He might believe that by getting rid of Naruto, he can maintain the status quo in the village and prevent any disruptions that Naruto's presence might cause in the future.
Perhaps he blames ninjas in general for the loss of someone close to him. For example, if a group of rogue ninjas were responsible for the death of a dear friend or family member, it could make him resent the whole ninja concept. He might think that if there were no ninjas, such tragedies wouldn't occur.
One difference could be his appearance. He might have a more menacing or stealthy look, with special ANBU gear. His attitude could also change. Instead of being as open and friendly as in the original series, he'd be more reserved and secretive.
Sasuke could be one of the characters. Maybe in a story where he has been corrupted by power and he sees Naruto's influence in Konoha as a threat. He devises a plan to trick Naruto into a marriage that would make Naruto lose his standing. Another could be Orochimaru. He is always up to no good and might want to use Naruto's power through his offspring. So, he could trick Naruto into marrying one of his subordinates who is under his control.
Sasuke could potentially be an ally. Since they have a complex relationship, Sasuke might understand Naruto's situation and choose to side with him against the village. Also, characters like Jiraiya could still believe in Naruto and help him from the shadows.
Another possible partner could be Hinata. She is very kind - hearted and detail - oriented. She could be in charge of customer relations, making sure that every customer feels welcome and satisfied. And her Byakugan might be used to keep an eye on the bank's surroundings for any signs of trouble.
One possible reason could be for Naruto's protection. Maybe Minato knew of some great danger that was coming for Naruto and he thought that banishing him would keep him out of harm's way. Another reason might be related to some prophecy or hidden power within Naruto that Minato feared could be misused if Naruto stayed in the village.
The Hidden Leaf Village elders could be the antagonists. If Naruto has gone against their rules and become an S - rank criminal, they would send out their best ninja to stop him. They might view Naruto as a danger to the stability of the village, even if his actions were for a good cause. This could create a very complex dynamic, as Naruto has to fight against the people he once called family.
Obviously, Naruto fans who also like cats would be interested. People who enjoy reading fan - made stories that add a unique twist to the original Naruto universe might also be into it.