Boruto might be in awe. He has always known his father as the Hokage, a powerful and respected figure. Seeing Naruto's past full of struggles, loneliness, and determination would make him realize how far his father has come. It could also make Boruto more empathetic towards Naruto and perhaps inspire him to be more like his father in some ways.
Well, he could be shocked. Boruto has grown up in a relatively peaceful time compared to Naruto's childhood. Naruto faced so much rejection from the village, and seeing all that might make Boruto feel sorry for his father. He might also start to understand why Naruto is so strict about certain things like hard work and never giving up. This could lead to Boruto having a newfound respect for Naruto's values.
Well, Boruto could be very inspired. Naruto's past is full of struggles, from not having parents around to being constantly underestimated. When Boruto discovers this in the fanfiction, he might realize that his own problems are not as big as he thought. He could be motivated to work harder and not take for granted the things he has, seeing how much Naruto had to fight for everything.
Probably his time at the Ninja Academy. Naruto was always getting into trouble there, but it was also where he made some of his first friends. Also, his encounters with the Third Hokage could be shown. The Third Hokage was like a grandfather figure to Naruto, and their interactions were important in Naruto's development.
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.
It could also be that Naruto sees in Boruto's eye a sign of an emerging danger. The eye might hold a clue to a new enemy or a brewing conflict. Naruto, being the experienced ninja he is, would then start to take precautions and train Boruto more intensively to face whatever this sign in his eye indicates.
Obviously, Naruto himself is a crucial character. His experiences and growth form the backbone of the story.
He might be shocked. Naruto has seen a lot in his life, but seeing something new and unexpected in his son's eye could still catch him off guard.
One interesting plotline could be exploring Naruto's early days of training with Jiraiya in more detail. Maybe showing his struggles and how he overcame them during that time.
One of the most shocking revelations could be Naruto's early days as an outcast. Boruto, who has always known his father as a respected figure, would be surprised to learn that Naruto was once shunned by the village. Another could be the danger Naruto faced as a young ninja, like fighting against the Akatsuki. It's so different from Boruto's relatively more sheltered life in the beginning.
Seeing Naruto's power in fanfiction can greatly influence Boruto's character. It could make him more determined to reach his father's level. He might start training harder and be more serious about his ninja duties.
His perception might become more complex. He'd see different interpretations of Naruto's actions and motives, which could make him realize that his father is more multi - faceted than he thought.