Some writers may write such fanfiction to subvert the common tropes. The Naruto - Sasuke relationship is so well - known and has been explored in so many ways in the original and in most fanfiction. By having Naruto not care about Sasuke, it challenges the status quo. It can also be a way to explore the consequences of such a change in their relationship. How would Sasuke react? How would it affect the other characters and the overall plot of the Naruto universe? There are a lot of interesting things to consider when taking this approach.
One reason could be to explore Naruto's character independently. Without the focus on his relationship with Sasuke, the writer can delve deeper into other aspects of Naruto's personality, like his dreams for the village, his relationships with other characters like Kakashi or Iruka. It's a way to break free from the over - emphasized bond in the original story.
One reason could be Sasuke's thirst for power. If he believes Naruto is the only obstacle in his path to ultimate power, he might be driven to kill him. In some fanfictions, Sasuke may be influenced by a dark entity that twists his mind into thinking Naruto is a threat that needs to be eliminated.
It could also be due to a misunderstanding. Perhaps there is some misinformation spread about Sasuke in the fanfiction, like false rumors that he has a hidden and malevolent plan. Naruto, being someone who values their friendship deeply, would be scared at the thought of Sasuke turning into an enemy because of these untrue stories.
It might be for creative exploration. Writers often like to play with established characters and relationships. By making Naruto not care about Team 7, they can explore new story directions and character interactions that wouldn't be possible in the canon story.
Some fanfic authors might write it as a form of wish - fulfillment. They might prefer the Naruto - Sakura relationship more than the Sasuke - Sakura one. So, they create a scenario where Sakura turns to Naruto in a romantic way. Additionally, it could be a way to explore the characters' personalities further. For example, how Sasuke would handle being betrayed and how Naruto would deal with being involved in such a situation. It gives a chance to dig deeper into their emotional and moral aspects.
It could also be a way for the writer to express their own dissatisfaction with the original relationship between Sakura and Sasuke. Maybe they felt that Sakura's character was not well - developed in the context of that relationship and decided to create a more 'dramatic' storyline through cheating.
Maybe Naruto was trying to protect Sasuke from a certain danger. There could be a curse or a powerful enemy that targets male shinobi. So, Naruto uses a risky jutsu to transform Sasuke into a girl to keep him safe. Or it could be that Naruto found a strange ancient scroll with a transformation technique that he thought was something else and when he used it on Sasuke, it turned him into a girl.
One possible reason could be jealousy. Maybe fem Sasuke is jealous of Naruto's natural charisma or his ability to make friends easily. Another reason might be related to their different goals. If fem Sasuke has a very different view of how to save or change the ninja world compared to Naruto, it could lead to hatred.
One possible reason could be his deep connection with Naruto in the original story. Fanfiction might offer new and different perspectives on their relationship, which intrigues him. Maybe he wants to see how others interpret their bond, whether it's their friendship or the complex rivalry. Another reason could be that fanfiction allows him to exist in scenarios that didn't happen in the official storyline, giving him a chance to explore different aspects of his character and his interactions with other characters.
One reason could be that Sasuke realizes he needs Naruto's unique abilities. Naruto has the Nine - Tails' power which could be useful in a certain task. So he takes Naruto with him to achieve a common goal.
Another reason might be related to their different ideologies within the ANBU. Naruto may have believed in a more collaborative and friendly approach within the organization, while Sasuke might have been more focused on individual achievement and power. This fundamental difference could lead to Naruto hating Sasuke in the fanfiction.