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.
Naruto might initially be in shock. He has always idolized his mother, so if she suddenly hurts him, he would be completely taken aback. He might freeze for a moment, unable to believe what is happening.
Naruto would probably be very confused at first. Kushina is his mother, so her hurting him would go against his understanding of their relationship. He might initially try to talk to her, to find out what's wrong and if there's a way to fix it.
Well, it could have a huge impact. If Kushina hurts Naruto in the fanfiction, it might make Naruto more distrustful. He could become more withdrawn and have to work harder to build relationships later on.
One possible fanfic could be about Kushina's early days in the Hidden Leaf. It might explore her training as a ninja, her relationships with her peers, and how she was perceived in the village. Maybe it delves into her friendship with Mikoto and how they supported each other during their pregnancies.
Perhaps she's under the influence of a powerful genjutsu. Genjutsu can distort one's perception and make them do things they wouldn't normally do. In this case, Kushina might be seeing Naruto as an enemy in the genjutsu and thus hurt him. Or it could be a test in a very extreme way. She might think that by putting Naruto through pain, she can make him stronger, although this is a very cruel way of thinking.
Perhaps in the 'naruto bangs kushina fanfic', there is a plot where Naruto discovers a hidden power within Kushina that was never explored in the main series. This power could be crucial in saving the village from a new and powerful threat. He then has to work with Kushina to harness this power and protect their home.
One possible reason could be for his safety. Konoha is a well - protected village with many skilled ninja. She might believe that leaving him there would ensure he has the best chance at survival and growth as a ninja. Also, she may have some mission or obligation that forces her to leave him behind, perhaps something related to the greater good of the village or the ninja world in general.
Yes, there might be such fanfics out there. The Naruto fandom is quite large and diverse, with fans creating all sorts of stories. However, these types of fanfics often deviate from the original canon storylines. You can try looking for them on popular fanfic websites.
Definitely not. In the Naruto world, there are established relationships and a moral code. 'Taboo fanfic' usually means it's violating those norms. It can be disrespectful to the original work and its fans who enjoy the series for its positive aspects like friendship, hard work, and family values.