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.
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.
They could become friends. Naruto is known for his ability to befriend almost anyone, and Rogue, despite her often - lonely situation due to her powers, could be drawn to Naruto's positive and friendly nature. They might start by sharing their stories - Naruto about his life as a ninja in Konoha, and Rogue about growing up as a mutant.
A romantic relationship might also be possible. Despite coming from different universes, they could be attracted to each other's unique qualities. The vampire might be drawn to Leia's courage and beauty, and Leia could be intrigued by the vampire's mystery and power. However, they would have to overcome many obstacles, like the differences in their natures and the fact that they are from different fictional worlds.
In fanfiction, they could have a sort of brotherly relationship. Boruto might see Kid Naruto as a younger version of his father, but also as an individual with his own charm. They would play pranks on people together, and when it comes to serious ninja business, they would have each other's backs. Boruto would protect Kid Naruto from some of the tougher enemies he might not be able to handle yet, and Kid Naruto would keep Boruto's spirits high with his positive attitude.
They could become very close friends. They share their adventures, stories about their favorite Pokemon, and their dreams for the future of the Pokemon world. They might even start to rely on each other emotionally, knowing that they are two of the most powerful trainers and can understand the pressures that come with that status.
A mentor - mentee relationship could develop. Tsunade could teach Naruto more about chakra control for his Rasengan, and Naruto could show Tsunade the value of never giving up. They could also become friends, with Naruto making Tsunade laugh more often and Tsunade giving Naruto advice on handling the more political aspects of being a ninja in the village.
They could become friends. Naruto has a way of befriending people from different backgrounds. Mito would be intrigued by Naruto's modern - day ninja skills and his unique personality. They could share stories about their lives, with Naruto talking about his friends and adventures in Konoha, and Mito sharing tales of the early days of the Hidden Leaf and her relationship with Hashirama. Through these exchanges, a strong friendship could form.
One possible plot could be that Sakura, on a mission in a far - off land, encounters Kisame. At first, they are enemies as Kisame is from the Akatsuki and Sakura is a Konoha ninja. But then, they find themselves in a situation where they have to work together to survive against a greater threat, like a powerful ancient beast. As they fight side by side, they start to understand each other's motives and pasts, and Sakura begins to see that Kisame is not just a mindless villain.
Well, it could start with Sakura growing up in a different environment due to her relation to Kisame. Maybe she has some of his physical traits like his blue skin in a more human - like way. And she might be trained in different fighting styles that are a mix of Kisame's and the regular ninja training she gets in the village.
One way it could develop is through shared experiences in the medical field. Sakura is a great medic - ninja, and Neji could get injured on a mission. This event could bring them closer as Sakura nurses him back to health and they start to see each other in a new light.