In a fanfiction where Naruto acts like Sesshomaru, the dynamic in the Naruto universe would be completely shaken up. Naruto's relationships would be the most affected. His friends like Sakura and Kakashi would be at a loss as to how to deal with this new Naruto. He would no longer be the one to quickly jump into a fight without thinking. Instead, he would assess the situation more carefully, like Sesshomaru. His appearance might not change much, but his aura would be completely different. He would carry himself with an air of superiority and detachment, which would be a huge contrast to his normal self.
If Naruto acts like Madara in the fanfic, he may begin to view the ninja world in a more cynical way. He could start to question the current system of peace and might try to reshape it according to his own vision, which would lead to battles with those who oppose him. Also, his relationships with characters like Sasuke would take a new turn, perhaps becoming more of a rivalry based on different ideologies.
The character development would be quite drastic. Naruto would start to lose his naivete and become more world - weary. He would stop believing in the good of everyone so easily as he used to. His interactions with his enemies would change from trying to understand them to simply seeing them as obstacles to be removed. This is a big shift from his normal character who always tries to find a way to redeem his foes.
Sesshomaru would likely be aloof and haughty at first. He might look down on Naruto as a mere human. Naruto, being his friendly self, would probably be curious about Sesshomaru and try to start a conversation. Sesshomaru might respond with cold remarks, but Naruto's persistence could gradually break through his icy exterior.
Sakura would be worried sick. She'd try to figure out what happened to Naruto to make him act this way. She might try to talk to him, use her medical ninjutsu to check if he's under some kind of genjutsu or has some other problem. She'd be very vocal about her concerns and would try to get the other villagers to help bring Naruto back to his normal self.
In a 'naruto acts like gin fanfiction', Naruto might be quieter and more observant. Instead of his usual boisterous self, he could be more like Gin, who is often sly and calculating. Maybe he would have a more subdued way of showing his power and a different approach to his enemies.
It could be really wild. Naruto's energetic and friendly nature would contrast with Sesshomaru's cold and aloof personality. Maybe there would be a story about how Naruto discovers his connection to Sesshomaru and has to navigate the Inuyasha world with his ninja skills.
The other Konoha ninjas would be quite shocked. The Hokage, whoever it is at that time, would see Naruto's change as a potential threat to the village's stability. They would likely keep a close eye on him and try to figure out what caused this transformation. Meanwhile, the younger generation of ninjas who looked up to Naruto would be confused and disappointed. They expected Naruto to be their role model of a kind - hearted and positive ninja, not someone acting like the feared Madara.
Naruto's character would likely become more aggressive. Yujiro is a very aggressive character, and Naruto might start to show similar traits. He could be quicker to anger and more assertive in his actions.
Well, in a Naruto in Ancient Greece fanfic, Naruto could be a Spartan warrior. He'd use his ninja skills in the Greek battlefields. His shadow clones could be like an army of Spartans, confusing the enemies. His Rasengan might be seen as some sort of divine power. And he'd probably have to face off against Greek monsters too, using his quick thinking and ninja training.
Well, if Naruto was a Jedi Master, he'd probably use his chakra in unique ways within the Jedi framework. His determination and never - give - up attitude would make him a great Jedi. He might teach other Jedi his ninja skills, like how to move stealthily. And his Rasengan could be transformed into some sort of Jedi - like energy attack. Maybe he'd form a special bond with his lightsaber, just like he did with his kunai in the Naruto world.