Well, first of all, Minato would likely be shocked. Naruto's past was full of hardships and loneliness. Minato would probably experience a mix of emotions. He might be sad that Naruto had to endure so much pain. He could also be proud of how Naruto overcame all those difficulties and still managed to grow into a strong and kind - hearted person. He might even try to find ways to comfort Naruto in this fanfiction world, like giving him some long - lost family memories or advice that could have made his journey easier.
The aftermath could be Minato's quest for revenge if Naruto's death was caused by someone. He would use his skills and knowledge to track down those responsible. Or, he could be plunged into a deep depression. He might isolate himself from the other spirits or entities in the afterlife. His whole existence could become centered around his grief and his memories of Naruto.
The plot might involve Naruto crying due to a misunderstanding with his friends. Kakashi witnesses this and steps in to mediate. He first calms Naruto down and then arranges for Naruto and his friends to have an open conversation. During this process, Kakashi shares some wisdom about friendship and communication, helping them resolve their differences.
Minato would likely be devastated. He sacrificed his life for Naruto, hoping for a great future for his son. Seeing Naruto die would shatter his hopes and dreams. He might first be in denial, unable to believe what he's seeing. Then, his grief could turn to anger, either at the situation or at those he believes are responsible. It's a tragic scenario that would change Minato's afterlife perception and his sense of purpose, which was always tied to Naruto's well - being.
One great Kakashi and Minato fanfiction is 'The Legacy of a Teacher'. It beautifully portrays Minato's influence on Kakashi. Another is 'Mentor and Student's Bond'. It delves deep into their relationship during Kakashi's early days. And 'Minato's Unfinished Business' is also a good read, showing how Minato's spirit might guide Kakashi in later challenges.
Kakashi may also get angry. Angry at the people or things that caused Naruto to get those scars. This anger could fuel his determination to make Naruto stronger, so that he can better defend himself in the future. He might then intensify Naruto's training, all while having a new - found sense of protectiveness towards Naruto.
One possible plot development could be that Minato uses the knowledge of Naruto's past to help him train better. Maybe he reveals some hidden family jutsu or techniques that Naruto can use to become even stronger.
The fanfiction 'Minato's Last Words to Kakashi' is extremely emotional. It focuses on Minato's final moments and the words he leaves for Kakashi, which are full of love and hope. Another one is 'Kakashi's Regrets about Minato'. It shows Kakashi's inner turmoil over things he wishes he could have done differently with Minato.
Some Minato and Little Kakashi fanfictions might focus on the political and social environment of the Hidden Leaf Village at that time. How did this environment affect their relationship? For instance, the village's expectations of its ninja, the power dynamics among different clans, and how Minato and Kakashi navigated through these aspects. It could also be about how their relationship was perceived by others in the village. Maybe some were jealous of Kakashi for having such a great sensei, or perhaps they saw the potential in their partnership for the future of the village.
In a fanfiction, Kakashi and Minato could be on a mission together in a dangerous, unknown territory. There could be traps everywhere. Minato, being the faster one, might rush ahead to scout but accidentally trigger a trap that causes some damage to him. Then, when Kakashi tries to help, he might also get injured by the after - effects of the trap or other hidden threats in the area.