Their relationship can be explored through flashbacks. For example, Minato could have left behind memories or messages for toddler Naruto that are revealed as Naruto grows. Another way is to have Minato's spirit interact with toddler Naruto, like guiding him in his dreams. They could also explore their relationship by showing how Minato's traits are already starting to show in toddler Naruto, such as his determination.
One plot idea could be Minato somehow being brought back to life for a short time and getting to spend precious moments with toddler Naruto. He could teach Naruto some basic ninja skills that Naruto would later forget but unconsciously use in his training. Another idea is a story where toddler Naruto is in danger and Minato's spirit appears to protect him, guiding Naruto to use his own latent powers. And perhaps a story where Minato's memories are transferred to toddler Naruto, giving him flashes of his father's life.
In fanfiction, Naruto and Minato often represent a connection between generations. Minato was a great ninja in his time, and Naruto is following in his footsteps. Fanfictions can explore how Naruto lives up to his father's reputation.
I'm not sure if there is such a specific fanfiction. Fanfiction can cover a wide variety of themes and scenarios, some of which might be rather strange or controversial. However, Naruto fanfiction often explores different relationships and alternate storylines, but this particular one seems a bit unorthodox and I haven't personally come across it.
One popular theme is Minato getting to know Naruto in the afterlife. Since Minato died when Naruto was a baby, fanfictions often explore their relationship in a spiritual realm.
One of the main similarities is their self - sacrifice. Minato sacrificed himself to save the village and his son. Naruto has also shown that he is willing to put himself in harm's way for the greater good. He's always the first to jump into a dangerous situation if it means protecting those he loves. Another aspect is their leadership qualities. Minato was a great leader as Hokage, and Naruto has developed into a great leader as well, inspiring those around him.
Minato would likely be extremely shocked. Naruto is his son, and the idea of Naruto attacking him would be completely unexpected. He would probably try to talk to Naruto first, to find out what is wrong and why he is being attacked.
There is a fanfiction that delves into toddler Naruto's relationship with Iruka Sensei. In this story, Iruka discovers Naruto as a toddler all alone and decides to take him under his wing earlier than in the canon. This creates a really heart - warming bond between them from a very young age. The story also shows how Naruto's early experiences with Iruka shape his view of the world even at that tender age.
You can try websites like Fanfiction.net or Archive of Our Own (AO3). They have a vast collection of Naruto fanfictions. Just search for 'Minato' and 'Naruto' in the search bar, and you'll get a list of relevant stories.
Minato could also teach Naruto about leadership. As the Fourth Hokage, he led Konoha. He could share his experiences on how to make tough decisions for the good of the village and its people. He might tell Naruto stories of past battles and how he strategized to win, which would help Naruto in his future as a leader in Konoha.