It could be that Naruto is scared of Kushina at night in the fanfiction because he has seen some strange visions or apparitions related to her. In the world of Naruto, there are many supernatural elements. Maybe there is some sort of genjutsu or spiritual influence that makes Naruto fear her at night. Also, it might be related to the power imbalance. Kushina was a very powerful ninja, and at night, when everything is more mysterious, Naruto might feel more intimidated by her strength.
One possible reason could be that Naruto has heard some spooky stories about Kushina from the past. Maybe there are tales in the village that at night, Kushina had a more intimidating presence due to her strong personality and powerful chakra. Another reason might be that Naruto has some sort of premonition or nightmare related to Kushina at night, perhaps linked to some hidden family secrets or events that he is unconsciously aware of.
One possible reason could be that Kushina has a very strong and intimidating personality. In the Naruto universe, she was known to be a tough kunoichi. Naruto, who might be used to more gentle or reserved people around him, could be scared of her boldness.
In this fanfiction, Naruto's fear of Kushina at night can show his vulnerability. Despite being a strong ninja, he has this fear which makes him more human. It can also be a way to explore his relationship with his mother. His fear might lead to him trying to understand more about Kushina and their family history.
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.
It could also be related to some hidden family secrets or prophecies. Maybe there was a prophecy that Naruto would bring great destruction in the future and Kushina, believing in it, thought she had to stop him before it was too late. This would be a very complex and heart - wrenching betrayal if it was based on such a false premonition.
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 that she later realizes Naruto's true nature and potential. Maybe she sees how strong and kind - hearted he is despite the hardships he faced. She might regret not being there for him during his growing - up years when he needed a mother figure.
One possible reason could be mind control. Maybe an enemy of the village found a way to manipulate Kushina's mind and make her turn against her own baby. Another reason might be a misunderstanding. For example, she could have been tricked into believing that Naruto was a threat to the village in some way.
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.
Maybe in this fanfiction, there was some sort of dark magic or mind - control involved. Kushina could have been unknowingly influenced to do something that deeply hurt Naruto. Like she was made to abandon Naruto at a crucial moment in his life, which then led to his hatred.