It could also be related to some prophecy or ancient rule in the fanfiction's world. Kushina might have been bound by a rule that stated she had to abandon Naruto to protect the greater good. This could involve things like preventing a greater disaster or fulfilling a necessary sacrifice for the village's future.
Maybe in this fanfiction, Kushina was under some sort of mind - control or false information. She might have been tricked into believing that leaving Naruto was for his own good. It could be that an enemy made her think Naruto would be safer without her around.
One possible reason could be that Kushina was forced to leave Naruto due to some external threat she thought would endanger him more if she stayed. For example, if there were powerful enemies after her and she feared they would use Naruto to get to her.
I think Minato could also be a main character. As Naruto's father, he might play a role in Naruto's life even though Kushina is absent. He could be a guiding figure or a source of mystery for Naruto, especially if Naruto discovers things about his father in relation to his mother's absence.
One possible reason could be for Naruto's protection. Maybe she thought by banishing him from a certain place or situation, she could keep him away from a hidden danger that she knew about. For example, there might be a powerful enemy targeting Naruto specifically, and she believed that by making him leave, he would be harder to find.
In the 'naruto rejects kushina fanfiction', it could be due to a sense of self - discovery for Naruto. He may be on a journey to find his true identity and purpose, and he believes that Kushina somehow stands in the way of that. Maybe he has new friends or allies in the fanfiction that he values more and their ideals are contrary to Kushina's. So, to stay true to these new relationships and his own evolving self, he rejects Kushina.
One possible reason could be some sort of dark force influencing Kushina's mind. Maybe she was under a powerful genjutsu that made her think she had to abandon Naruto for his own safety, even though it was a false perception.
One reason could be to explore the darker side of family relationships. In the Naruto world, family is often portrayed in a positive light, and this could be a way to show what could go wrong. Another reason might be to create a unique and attention - grabbing plot.
One possible reason could be some sort of dark influence or curse that makes her lose her maternal instincts. Maybe a powerful enemy targets her and in order to protect Naruto from further danger related to her, she feels forced to abandon him. Another reason might be that she is made to believe false information about Naruto, such as that he will bring great disaster to the village in the future.
One possible reason could be a mission. In many Naruto - related stories, missions often take characters away from their families. Naruto might have received a highly important and dangerous mission that requires him to be away from Kushina for a long time.
Maybe she's been possessed. In some fanfictions, characters can be taken over by dark forces. So Kushina could be under the control of some evil entity and that's why she hurts Naruto.
It could also be due to some external influence. Perhaps an enemy used some kind of mind - control or manipulation on Kushina. They made her think that Naruto was a threat, so she decided to disown him. In the Naruto universe, there are many powerful villains who could potentially do this kind of thing.
As he grows up, Naruto could become very angry. He might develop a sense of abandonment and this could fuel his determination to become stronger. He would want to prove himself to his mother, wherever she is. In this fanfiction, his anger could be a driving force in his character development.