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.
One possible plot could be that with Minato and Kushina alive, Naruto grows up in a complete family. They could train Naruto together, passing on their unique jutsu. Maybe Minato could finally fulfill his dream of bringing long - lasting peace to the Hidden Leaf with his family by his side. And Naruto would have a different kind of confidence and growth, not having to face the loneliness he did in the original story.
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.
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.
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.
One possible plot twist could be that with Minato and Kushina alive, Naruto's training would be completely different. Minato, being a prodigy, could teach Naruto advanced jutsu much earlier. And Kushina might pass on some unique Uzumaki clan techniques. Maybe they would also change the political situation in Konoha, as Minato was a highly respected Hokage. This could lead to different alliances and power dynamics within the village and among the other ninja villages.
Perhaps in this fanfiction, Minato and Kushina leave Naruto because they are cursed. They fear that the curse will harm Naruto if they stay close. So, they go into exile. As Naruto grows up, he starts to discover clues about his parents' real reason for leaving and sets out on a quest to find them and break the curse. This could lead to many adventures and character - development moments for Naruto.
One possible plot could be Minato and Kushina looking on with pride as Naruto marries Hinata. They might be reminiscing about their own relationship and how far Naruto has come. They could also be interacting with the other guests, sharing stories of Naruto's childhood that the others may not know.
One possible plot could be that Minato and Kushina are somehow brought back to life in a spiritual or semi - physical form. They then embark on a journey through the ninja world to find Naruto. Along the way, they encounter various characters who either help or hinder them. Maybe they have to face some old enemies who are still lurking in the shadows and trying to stop them from reuniting with Naruto.
One idea could be exploring how Kushina and Minato's relationship influenced Naruto's growth. For example, in the fanfic, Naruto could discover old letters from his parents that reveal their hopes and dreams for him. This would add an emotional depth to his character.
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.