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.
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.
Well, it could be that the fanfiction is set in a very different universe where Naruto has different upbringing or experiences. But this is quite a stretch because Naruto's caring side is so deeply rooted in his story. It might also be that the writer is simply trying to create shock value by presenting such a counter - intuitive view of Naruto. But in general, it's not in line with the essence of Naruto as we know him from the original series, and it might be a bit of a gimmick to make the fanfiction stand out in a sea of more traditional Naruto stories.
It could be that she has some past trauma related to Naruto's birth or the events surrounding it. For example, if she had a difficult pregnancy or if there were some threats to Naruto's life right from the start that made her distance herself out of fear. Another possibility is that she is under some sort of mind control which makes her act as if she doesn't care.
It could also be due to some sort of mind - control or curse. In the Naruto universe, there are many powerful jutsus and dark magics. Perhaps an enemy has cast a spell on him that makes him not care about his own life. This would be a dangerous situation as he could be easily manipulated into dangerous situations without self - preservation.
It could also be due to Sasuke's secrecy. If Sasuke is constantly hiding things from Naruto, like his real intentions or new powers he's acquired, Naruto would naturally start to feel that he can't trust him. Trust is built on honesty and openness, and if Sasuke is being cagey, Naruto's trust in him will fade.
One possible reason could be a misdirection in his goals. If in the fanfiction he is overly focused on proving himself to the village, he might think that family is a distraction. So, he starts to distance himself from his family to concentrate more on getting recognition from the village.
Naruto could become more self - centered. Since he no longer has the overarching goal of protecting Konoha, he might focus more on his own needs and desires. For example, he could pursue personal power or adventure without considering the implications for the village.
In the fanfiction, it could be that Sasuke's unyielding thirst for power and his disregard for the consequences of his actions on those around him are reasons Naruto doesn't forgive him. Sasuke was so focused on his own goals that he often trampled on the feelings and safety of others, and Naruto, who is all about protecting and connecting with people, may find it hard to forgive such self - centered behavior.
One reason could be the author wants to create a unique and edgy story. By making Harry Potter not care about anyone, it's a complete subversion of the well - loved character. It grabs readers' attention.
One possible storyline could be that Naruto has faced so many disappointments that he decides to isolate himself from the Hidden Leaf Village. Maybe he feels betrayed by the people he once trusted, like some of the village elders. He might then embark on a journey alone, exploring new lands and meeting different shinobi cultures.