They could form an unlikely friendship. Naruto's positive attitude might gradually influence Kisame. And Kisame's teachings would also make Naruto see him in a new light. They could start to trust each other more and even become comrades in some special situations.
At first, it would be full of suspicion. Naruto is a Konoha ninja and Kisame is from the Akatsuki. But as the teaching progresses, they might develop a mutual respect. Naruto would respect Kisame's power and knowledge, and Kisame might respect Naruto's determination.
The relationship could be complex. On one hand, Naruto would always be aware of Kisame's past actions as an Akatsuki member. On the other hand, Kisame might have his own hidden motives for teaching Naruto. This would create a lot of tension and drama in their relationship as the story unfolds.
Kisame would probably be very angry at first. Samehada is his weapon and has been with him for a long time. He might feel betrayed and try to get Samehada back by force.
Naruto would likely become more reserved. Since Kisame is not as expressive as some of Naruto's friends in the Leaf Village, Naruto would pick up on that. His fighting style would also change. He'd probably be more stealthy and calculating, learning from Kisame's experience. For example, instead of his usual head - on attacks, he'd start to use more misdirection and ambush tactics.
Naruto's character would likely become more reserved in some ways. With Itachi's influence, he'd think more before acting. But he'd also become stronger and more confident. Kisame's tough training would make him physically tougher. Naruto might also start to question some of the things he learned in the village, as Itachi and Kisame have different perspectives.
Naruto's character might become more calculating. Kisame is a very strategic fighter, and Naruto could pick up on this trait. He would start to think more before acting in battles.
Iruka could be an important character. He's always been like a father figure to Naruto, and now with this new revelation, he might have to help Naruto deal with it. Hinata could also be in the story, and her feelings for Naruto could be complicated by his connection to Kisame. And then there could be some original characters created just for this fanfiction, like a ninja who was a former ally of Kisame and has some information for Naruto.
Their relationship could develop into a mentor - mentee bond. Naruto would respect Mei as his teacher and look up to her for guidance. Mei, on the other hand, would see Naruto's potential and be proud of his progress.
There could be. Fanfiction is a vast realm where all sorts of ideas are explored. However, I'm not sure if there is a highly popular or mainstream 'naruto is kisame apprentice' fanfiction. It might be a more niche concept, but it's entirely possible that some creative writer has delved into this idea to create an interesting story about Naruto learning from Kisame, perhaps incorporating Kisame's unique fighting style and view of the ninja world into Naruto's growth.
Naruto might gain a different perspective on the ninja world. Kisame has his own view as a member of the Akatsuki. Through Kisame's teachings, Naruto could understand the motives and thoughts of the 'villains' better, which could help him in future battles and negotiations.
Well, in some fanfictions, Naruto might defeat Kisame in a battle and take the sword as a trophy. Maybe he uses his newfound Sage Mode powers or some other advanced jutsu to overpower Kisame and claim the sword.
A mentor - mentee relationship could potentially form in some fanfictions. Maybe Sakura is trying to learn more about water - based jutsu and she approaches Kisame (since he is very proficient in water techniques). At first, Kisame is reluctant but then he sees her potential and decides to teach her a thing or two. This would lead to a lot of interaction between them and a unique bond.