In some cases, Naruto might initially become bitter towards his parents. But as he experiences more in life and learns about the possible reasons behind their actions, he could come to understand and even forgive them. His reaction would also depend on the people around him. If he has good friends or mentors, they could help him deal with his emotions in a more positive way.
They would be absolutely devastated. Minato, as Naruto's father, would likely be filled with guilt for not being there to protect him. Kushina, as his mother, would be heartbroken. They might first be in a state of shock, unable to believe what has happened. Minato might blame himself for leaving Naruto alone in a world full of dangers. Kushina would probably hold Naruto's body close, crying uncontrollably, and their grief could be so overwhelming that it would change the entire course of the ninja world they live in as their connection to Naruto was a major part of their lives.
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.
There's a fanfic called 'Minato's Return'. In this story, Minato somehow returns and gets to see Naruto's growth. It's really interesting to see how he interacts with Kushina, who is also there in the story, and how they both guide Naruto in new ways. The descriptions of their family bond are heartwarming.
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.
Minato would probably be very proud. He might notice Naruto's use of his own jutsu and be impressed by how Naruto has developed his skills. Kushina would be more emotional, maybe crying at the sight of Naruto growing up so well.
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.
Well, in some fanfictions, the moment when Minato sacrifices himself to save the village while Kushina is already dead is extremely emotional. It shows his selflessness and also the love he has for the village and his family. Also, the flashbacks in some stories about their early days together, like when they trained together as young ninjas and slowly fell in love, are really sweet and emotional.
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.
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.