Perhaps in the fanfiction's plot, there are some dark secrets associated with Minato and Kushina. Maybe they were involved in something that Naruto, with his strong sense of justice, couldn't forgive. For instance, if they were unknowingly part of a plot that caused harm to the village or its people in the past, and Naruto discovers this, it could fuel his hatred.
In some fanfictions, it could be due to a different upbringing. If Naruto was raised in an environment where he was constantly told false things about Minato and Kushina, he might develop hatred towards them. For example, if he was led to believe they abandoned him on purpose instead of sacrificing themselves for the village.
One possible reason could be a miscommunication in the fanfiction. Maybe some secrets were kept from Naruto about his parents that made him feel betrayed when he found out, thus leading to hatred.
At first, Naruto and Kushina might start to distance themselves from Minato. They could avoid him and not talk to him as much. As time goes on, the hatred might grow deeper. Naruto could start to oppose Minato in public or in important village matters. Kushina might also try to influence others in the village against Minato.
It might be due to jealousy. If Minato was getting more attention or praise in the village for his achievements while Kushina felt overlooked, that could create resentment. Say, Minato was constantly being hailed as a hero for his speed and battle tactics, and Kushina, who also had great power, felt like she was in his shadow.
In some fanfics, Naruto might be made to hate Minato and Kushina due to a sense of abandonment. If the story is written in a way that emphasizes how Naruto grew up alone and suffering, he could project his anger onto his parents for not being there for him. For example, he might think that if they were alive, he wouldn't have had to endure the taunts and loneliness in the village.
In many Naruto fanfictions where Naruto meets Kushina and Minato, it often creates a very emotional scenario. Naruto finally gets to meet his parents who he has only heard about. It could be a heart - warming reunion where they share stories, hugs, and Minato and Kushina get to see how far Naruto has come.
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.
Well, it could be related to Minato's absences. He was often away on important ninja business. Naruto might have felt abandoned by his father, and Kushina, seeing her son suffer in Minato's absence, could start to resent Minato. Also, there might have been some political decisions Minato made that didn't sit well with Kushina. For example, if he made an alliance that she thought was against the values of the village or their family.
In a fanfiction, perhaps Minato and Kushina are resurrected during a powerful enemy attack on the village. Naruto is in the middle of the battle when he suddenly sees his parents. At first, he can't believe it. Kushina runs to hug him tightly, while Minato stands there with a proud look. They then join the fight together, using their combined skills to defeat the enemy and have a moment of family reunion.
One possible fanfiction could be about Minato and Kushina watching over Naruto from the afterlife as he grows into a great ninja. They could be his silent guardians, influencing his decisions in subtle ways.
A fanfiction could center around a family training session. Minato trains Naruto in advanced ninjutsu techniques while Kushina teaches him about the Uzumaki clan's secrets. This would not only strengthen their family bond but also make Naruto an even more powerful ninja.
Well, I really like 'The Uzumaki Trio'. In this fanfiction, it shows the strong family unit of Kushina, Minato, and Naruto. It has great character development and some really touching moments. 'Minato's Promise' is also good. It's about Minato making a promise to Kushina before his death and how Naruto discovers this later. And 'Kushina's Strength' is a fanfic that emphasizes Kushina's power and how she and Minato complement each other.