In this fanfic, Naruto is the key figure. However, other characters like Shikamaru cannot be ignored. Shikamaru is known for his intelligence. Naruto might turn to him for help in devising strategies based on the future he has seen. Also, characters from other villages such as Gaara might be important if Naruto sees future events that involve interactions or conflicts with other villages.
Naruto is the central character, no doubt. Hinata could be important as well. If Naruto sees a future related to his family or his relationship with Hinata, she will play a significant role. Additionally, the Hokage, like Tsunade or whoever is in charge at that time, would be important as Naruto may need to report the future he saw to the village leadership to take collective action.
Obviously Naruto himself is the most important as he's the one seeing the future. Sasuke would likely be there too, as he's Naruto's closest friend and rival. Sakura would probably also play a role, maybe as a skilled medical ninja in the future Naruto sees. Kakashi might also show up, perhaps as an elder guiding Naruto in his leadership role.
It could be a new character, perhaps someone from a far - off land who has a grudge against Naruto's future self for some reason. This character might be extremely powerful and has plans to destroy everything Naruto holds dear. When Naruto sees this future, he has to find a way to stop this new threat before it even begins to form.
Naruto might meet his future children. He would be able to see what kind of people they are and what their dreams and aspirations are. It would be an emotional moment for him, seeing his family in the future.
Obviously, Naruto himself is the most affected as he has to deal with the knowledge of the future. But his friends like Sasuke, Sakura, and Kakashi would also be deeply affected. If Naruto saw a future where Sasuke was in trouble, he would do everything to change it, which would impact Sasuke's life. Sakura, being Naruto's teammate and also caring about Sasuke, would be involved in any plan Naruto made. And Kakashi, as their sensei, would be there to guide and support them through the changes Naruto tries to make based on his future vision.
Maybe in the fanfic, Naruto sees a future where Konoha is destroyed. This makes him determined to change the future. He could start by strengthening the village's defenses, forging new alliances, and also trying to figure out the root cause of the destruction in the future he saw. He might also try to uncover any hidden threats within the village that could lead to such a catastrophe.
Well, perhaps Naruto sees the future where his friends are in great danger. So he tries to change the course of events. He might start to make different decisions in his present to avoid the bad future he has witnessed. For example, he could try to resolve conflicts with certain characters earlier to prevent future wars.
Obviously, Naruto would be the main character since it's about his past seeing the future. Sasuke would also be important as Naruto's relationship with him is central to the Naruto series. Kakashi too, as he is Naruto's teacher and mentor, and his guidance might be influenced by Naruto's new - found knowledge of the future.
The main characters are Naruto and his comrades. Iruka, Naruto's first teacher, could be in it too. He has always been like a father figure to Naruto. In the fanfiction, he might be one of the first to notice something strange about Naruto's future. Then there are Naruto's other friends from the village like Kiba and Choji. They would all react differently to seeing Naruto's future. Kiba might be more impulsive in his actions to change it, while Choji might be more cautious but still determined to help Naruto have a better future.
Maybe Naruto sees himself as Hokage, with the village prosperous and peaceful. He could see his friends by his side, all having achieved their dreams too.
Obviously, Naruto would be one of the main characters since it's about him seeing dead people. There might also be other characters like Sasuke, who could react to Naruto's new ability in different ways. And perhaps some of the dead characters he sees, like the Fourth Hokage, could also be considered main characters in the context of this fanfic as they play important roles in Naruto's story.