In this type of fanfiction, their relationship could be developed through Naruto finding a way to communicate with Kushina's spirit. Through this communication, Kushina can share her experiences of being neglected with Naruto. Naruto, in turn, can tell her about his own struggles. This exchange of experiences can create a stronger bond between them, and Naruto can then strive to make sure that no one else in the village feels the neglect that they did.
He might start to rely on his friends more. For example, Sasuke and Sakura could become his main source of emotional support. He would focus on training with them and sharing his feelings, which in turn helps him to grow stronger and more independent.
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.
For Naruto, you could show his growth in terms of his leadership skills when he's with Naruko and Kushina. He could learn to be more patient and understanding, especially when Naruko might have a different approach to things. For Naruko, her character could be developed by showing her struggle to be recognized in a world where Naruto already has a reputation. Kushina could be developed by exploring her motherly side more deeply, as she interacts with both Naruto and Naruko.
One possible reason could be a misunderstanding. Maybe Minato thought Kushina had done something to endanger Naruto when in fact she hadn't. In the heat of the moment, he lost his temper and slapped her.
The Naruto x Kushina romance in fanfiction can be quite interesting. Fanfic writers might focus on the idea of Kushina seeing Naruto grow up and be proud of him. They could have tender moments like Kushina helping Naruto with his studies or training. There could also be a plot where they face challenges together, like protecting the village from a new threat. This kind of fanfiction allows fans to imagine a different family dynamic for Naruto that he was deprived of in the original story.
Minato might be a common character. Since he is Kushina's husband in the original story, his presence can add an interesting dynamic. Also, Jiraiya could be there. He was Naruto's mentor and his interactions with the harem situation could be quite humorous.
In such a fanfiction, the relationship between Naruto and Kushina would be one of mother - son love and mutual respect. Kushina would be protective of Naruto and proud of the man he has become. Naruto would look up to Kushina and value her wisdom. With Hinata, Naruto's relationship would be that of a loving couple. Hinata would support Naruto in all his endeavors. When it comes to Kushina and Hinata, Kushina would likely see Hinata as a worthy partner for Naruto and Hinata would respect Kushina for being Naruto's mother and a strong kunoichi.
A plot could involve Naruto finding a hidden diary of Kushina's where she wrote about her feelings of being neglected. This could lead to Naruto having a new understanding of his mother and also make him question the way the village has treated him. Or perhaps in a different scenario, both Naruto and Kushina are sent to an alternate dimension where they are both neglected, and they have to rely on each other to find their way back while also dealing with their emotional baggage.
Their relationship could be developed through shared experiences. For instance, they could go on a mission together where they face a powerful enemy. During this mission, they would have to rely on each other's skills, which would deepen their bond.