Another possibility is that Naruto has been influenced by some external dark power. This power could be slowly corrupting his mind and making him see the Hokage as an enemy. It could be a new type of jutsu or an ancient evil that has latched onto Naruto and is using his strength to carry out its own malicious plans against the Hokage.
Perhaps the Hokage has made a decision that Naruto believes will destroy the village's future. Like if the Hokage decides to sacrifice a large number of innocent villagers in order to achieve a short - term goal. Naruto, with his strong sense of justice, might see killing the Hokage as the only way to stop this madness.
Well, it depends on how it's written. If it's just for shock value, it might not be a very good fanfic. But if the author has a well - thought - out plot that explains Naruto's actions, like if the Hokage has been secretly evil all along and Naruto discovers this and has to take drastic action, then it could be an interesting take. However, it's still a very controversial concept within the Naruto fan community.
Shikamaru is another possibility. He is known for his strategic mind. As Hokage, he could use his intelligence to make wise decisions for the village. He may not have the brute strength of Naruto or Sasuke, but his ability to plan and analyze situations would be invaluable in leading Konoha.
He would likely be seen as a traitor by the village. The villagers, who once saw Naruto as a hero - in - the - making, would now turn against him. He'd be hunted by the ninja forces of Konoha.
Sasuke could also be a possibility for the 6th Hokage in the fanfic. He has grown stronger over the years and his unique perspective on the ninja world could bring new ideas to the leadership of the Hidden Leaf. He might start off as a controversial choice but prove himself through his actions in protecting the village and making tough decisions.
Perhaps he would focus on his training and become a master of a new, unique form of jutsu. He might then open a dojo to teach the younger generation his skills, rather than aiming for the Hokage position. This way, he could still have a great influence on the ninja world.
In a fanfic, Naruto might be motivated to learn medical jutsu because he realizes that his strength alone isn't always enough. He's been in situations where he couldn't protect everyone, and medical jutsu would be another way to ensure their safety. Also, he may want to prove himself in a different area. He's known for his combat skills, but learning medical jutsu would show his growth and ability to adapt.
One possible plot could be Naruto dealing with the boredom of retirement. He might try to find new hobbies like gardening in Konoha. Maybe he starts teaching some young ninja in an unofficial way, passing on his unique skills and experiences.
One possible plot could be Naruto facing the challenges of rebuilding the village after a major war. He'd have to deal with political intrigue from within the village, like some clans trying to gain more power. Also, he might focus on training the next generation of ninja to be stronger and more united.
The fanfic might focus on the 6th Hokage's personal growth. He could start off with insecurities but as the story progresses, he overcomes them through various trials. For example, he might have to deal with a powerful rogue ninja who challenges his authority. In the process, he discovers new powers within himself and also learns more about the history of the ninja world. This growth not only makes him a better leader but also a more respected figure among the ninja community.
One possible reason could be that some elders in the village still have doubts about his past. For example, his connection with the Nine - Tails. They might fear that this could lead to instability in the village. Another reason could be political intrigue. There might be other powerful clans or individuals who want the position for themselves and manipulate things behind the scenes to deny Naruto.