One possible motivation could be his deep - seated longing for his parents. Naruto has always felt their absence and has craved their love and approval. Jumping in front of them could be his way of showing that he is worthy of being their son and that he can protect them, even if it's in a situation that defies the normal order of things. It's like he's trying to rewrite the past in a way, to be the hero for his parents that he has become for the village.
In a fanfiction, Naruto might jump in front of his parents out of a sense of justice. He has grown up believing in protecting the weak and doing what's right. His parents, being in a vulnerable position, would trigger his natural instinct to shield them. Also, Naruto may have heard so many stories about his parents that he feels a strong connection to them. He wants to prove to himself and them that he is the kind of person they would be proud of. He has faced so many challenges in his life, and this could be his ultimate test of character, to sacrifice himself for his family.
In fanfiction, Naruto jumping in front of his friends could be a heroic act. Maybe he's protecting them from an incoming attack. It shows his selfless nature, always ready to sacrifice for those he cares about.
Perhaps Naruto is poisoned by a powerful new villain. His parents are revived just in time to see him succumb to the poison. This event could trigger a series of events where his friends and the entire village vow to avenge his death. His parents might then decide to stay in the living world to help in this quest for vengeance, despite the rules of the afterlife.
In this fanfiction, Naruto, filled with new - found strength and determination, jumps in front of his parents. His parents, who have long been dead, look at him in shock and pride. Naruto stands tall, his eyes blazing with the will of fire. He tells them that he has come a long way, that he has faced countless enemies and hardships. He wants them to know that he is no longer the lonely, ostracized boy. His father, Minato, smiles and places a hand on Naruto's head, just as he did when Naruto was a baby. His mother, Kushina, hugs him tightly, her eyes wet with tears. Naruto then begins to tell them about his friends, his village, and how he has protected it all. He vows to continue to do so, with their love and support always in his heart.
Perhaps Naruto is tired of the pitying looks he gets from people when they see his scars. By hiding them with genjutsu, he can avoid those uncomfortable moments and be treated as just Naruto, the powerful ninja, rather than Naruto, the one with the scars. Also, he may not want his enemies to see his scars and think they've managed to truly harm him, so he uses genjutsu to keep up a facade of being unscathed.
Sasuke would be deeply affected. He and Naruto had a complex relationship, from being rivals to friends. He would likely feel a sense of guilt, as if he should have been there to protect Naruto. Sakura would be heartbroken. She had always cared for Naruto, and seeing him die in such a tragic way in front of his parents would make her feel helpless. His parents, on the other hand, would be in utter despair. His father might feel like he failed as a father again, not being able to protect his son this time either.
In some fanfictions, Naruto might find a super - powerful jutsu or artifact. For example, he could discover a long - lost forbidden jutsu that has the power to bring the dead back to life. Or perhaps he stumbles upon a magical item during one of his adventures that is said to be able to revive the deceased.
Another reason could be that Naruto is lured away by an external force. Some powerful figure or group might convince him that leaving his parents is for the greater good, perhaps in the name of protecting them or the village in a more effective way.
In such a fanfiction, Naruto might be overwhelmed with emotions. He could finally get to understand the sacrifices his parents made for him. His father, Minato, might share some of his jutsu secrets, and his mother, Kushina, would probably embrace him tightly, telling him how much she loves him.
Well, it could be that Naruto is on a mission and accidentally uncovers a powerful jutsu that has the power to show the past. And through this, he sees his parents. His father might give him some advice on how to become a better ninja or how to handle the power within him. His mother could tell him how much she loved him and why they had to sacrifice themselves. Then Naruto could use this new understanding to face his enemies more bravely.
One reason could be misinformation. If in a fanfiction, Naruto is fed false information about his parents' actions, he might come to hate them. For example, if he's told that his parents were responsible for a great tragedy that he believes in without knowing the truth. Another factor could be the feeling of abandonment. Since Naruto grew up alone, if a fanfic writer emphasizes this aspect and makes Naruto believe his parents willingly left him, he could hate them.