Maybe in this fanfiction, Naruto is in an alternate reality where he doesn't know Kushina is his mother. He might be misled by false information about Kushina being a threat. And when he confronts her, his hot - headed nature gets the better of him and he slaps her. But then, as the story progresses, he discovers the truth and regrets his actions.
One possible plot could be that Boruto does something really reckless, like using a dangerous jutsu without proper training. Naruto, as his father and the Hokage, slaps him to snap him out of his overconfidence and make him realize the seriousness of his actions.
One possible plot could be that Ino says something really offensive about Naruto's dreams or his past. For example, she might mock his early days as a weak ninja in the academy. Naruto, who has grown and become more confident, slaps her in a moment of anger to defend his pride. Then, he realizes his overreaction and feels guilty, leading to a story arc about making amends and understanding each other better.
In a fanfiction, if Minato were to slap Kushina, it would be a huge shock to the Naruto - Kushina relationship. It could potentially cause a rift between Naruto and his father Minato in Naruto's mind. Also, Kushina would likely be deeply hurt and angry, which might lead to her distancing herself from Minato. This event could also change the way Naruto views his family's past and his parents' relationship.
Some fans would be extremely shocked and angry. Kushina is a beloved character, and Naruto slapping her goes against the loving relationship they should have as mother and son. They might feel that it's a disrespect to the original story's characters and themes.
One possible plot could be that they have to face challenges together in a post - war Konoha. They might work on rebuilding the village while also dealing with their new family life. Naruto, with his experience and Kushina's strong will, could make a great team in leading the village in a new direction.
In this fanfiction, the plot might involve Kushina coming back to help Naruto in his toughest battles. Maybe she uses her unique chakra abilities that Naruto has inherited to give him an edge. She could also provide emotional support, as Naruto has always longed for his mother.
One possible plot could be that Naruto somehow inherits the Rinnegan from an unexpected source and Kushina, being his mother, helps him understand and control this new power. Maybe they discover a hidden connection between the Uzumaki clan and the Rinnegan's origin, leading them on a journey to uncover secrets long lost in the ninja world.
One possible plot could be that Naruto, with his powerful jutsu and leadership skills, takes charge in a situation where Kushina's safety is at stake. He might use his Rasengan to fend off enemies and dominate the battlefield, protecting his mother Kushina in the process.
One possible plot could be that Kushina's departure makes Naruto more determined to prove himself. He might strive harder in his ninja training, using the pain of his mother leaving as motivation. This could lead to him achieving new levels of power at a faster rate.
Perhaps there's a time - travel element involved. Naruto from the future, who has been through some horrible experiences, travels back in time and, in a state of confusion or rage, attacks Kushina. Or it could be that a powerful villain has the ability to manipulate Naruto's emotions and uses that power to make him turn on his mother. This would create a very complex and dark plotline that challenges the normal Naruto narrative.