Iruka could be one. He's always been like a mentor to Naruto. He might have some knowledge about Minato that he shares with Naruto. For example, he could tell Naruto about his father's kindness towards students at the ninja academy.
Well, in some fanfics, Naruto might first discover his father's identity through a hidden scroll. This could lead to him learning about his father's special jutsu. For example, he could find out about Minato's Flying Thunder God Technique and start training to master it himself, seeing it as a connection to his father.
In many fanfictions, it could be through finding old documents or letters. Maybe he stumbles upon a hidden scroll in his home that contains some information about his father. For example, it might be a letter from his father to his mother that gives some clues about his father's personality or his role in the village before Naruto was born.
When Naruto finally realizes the sacrifices his father made for the village and for him. For example, learning that his father sealed the Nine - Tails inside him to save the village at the cost of his own life. This realization can be a very emotional moment as Naruto understands the depth of his father's love and selflessness.
Well, in many such fanfictions, Naruto might start learning his father's jutsu when he discovers some hidden scrolls or when a mentor who knew his father decides to teach him. Maybe it could be someone like Jiraiya who reveals some secrets about his father's techniques.
One challenge could be the complexity of the jutsu itself. His father's jutsu might be very advanced and require a high level of chakra control that Naruto doesn't initially have.
Iruka could be a main supporting character. He has always been like a father figure to Naruto in a way. He could help Naruto process the new information about his real parents, providing emotional support and also sharing his own memories of Naruto growing up, which could contrast with the new knowledge about Minato and Kushina.
Another plot point could be Naruto meeting an old acquaintance of his parents. This person could share stories about how his parents met, their early days together, and the kind of people they were. For example, they might talk about how Kushina was a feisty and strong - willed woman, and how Minato was a prodigy with a kind heart. This would help Naruto see his parents as real people with their own personalities and not just as the heroes who sacrificed themselves for the village.
Obviously, Naruto himself is a key character as the story is about him learning his heritage. His mentor, like Kakashi, could also play an important role. Kakashi might notice some strange things about Naruto's abilities and start to suspect that there's more to his heritage. Then he could guide Naruto in the discovery process.
In the fanfic, Naruto may learn of his heritage through a new character. Maybe a mysterious ninja shows up who has some connection to his family. This ninja could start to train Naruto in ways that are specific to his family's ninja techniques, revealing more about his heritage as they train together.