The theme of identity could also be present. Naruto has always been searching for his identity. With Kushina in the story, he could gain more understanding of who he is through his connection to her, as she is an important part of his heritage.
Love and sacrifice might be another theme. Kushina sacrificed herself for Naruto. In the fanfiction, this could be explored further, like Naruto learning about that sacrifice in a more in - depth way and how it shapes his view of love.
A common theme could be family. Since Kushina is Naruto's mother, exploring their family connection would be natural. It could show how important a mother - son relationship is.
Another aspect could be that the fanfiction delves into how Kushina's presence affects Naruto's relationships with others. For instance, his relationship with Sasuke could be different. With a strong maternal figure in his life, Naruto might be more stable emotionally and be able to approach Sasuke in a more understanding way, which could potentially change the whole dynamic of their rivalry and friendship.
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.
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.
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.
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.
Another theme is legacy. Kushina was a powerful ninja, and Naruto inherited some of her traits. Fanfics can focus on how Naruto lives up to her legacy. He might learn from her techniques or her way of thinking. This shows how the past can influence the present and future in a positive way, as Naruto uses what he 'inherits' from Kushina to become a better ninja and a better person.
One reason could be that she lost so much time with Naruto due to her early death in the original story. So in the fanfiction, she's overcompensating for that lost time by being possessive.
On a more personal level, they could face internal guilt. As Naruto grows up and achieves great things on his own despite their neglect, Minato and Kushina may realize what they've missed out on. This realization could cause them a great deal of internal turmoil and regret for not being there for their son when he needed them.
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.