Minato's character could be developed by showing his growth from a young, talented ninja to a more mature and responsible leader. His relationship with Kushina can play a big part in this. For example, through his love for her, he becomes more empathetic. Kushina, on the other hand, could be developed by exploring her past and how it affects her actions. Her time with Minato helps her become more confident and less impulsive.
Naruto would be overjoyed to see his parents. Emotionally, it would give him a great boost. He would finally have the family he always dreamed of having around him.
One interesting storyline could be Minato and Kushina's first meeting. Maybe it was a chance encounter in the Hidden Leaf village. Minato, with his natural charm, caught Kushina's attention right away. Another could be their training together, where they learn new jutsu and grow closer as they support each other through tough training sessions.
Perhaps they return to impart some final wisdom to Naruto. Minato could teach Naruto some advanced sealing techniques that he hadn't mastered yet, and Kushina could share more about the Uzumaki clan's secrets and how Naruto can further harness his Uzumaki heritage.
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.
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.
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.
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.
I really like the fanfiction 'Kushina's Return'. It imagines a scenario where Kushina comes back to life and how she interacts with the characters in the Naruto Shippuden universe. It has some great emotional moments and cool fight scenes where Kushina shows off her skills.