Another possible reason is Minato's own experiences. Maybe he has faced a lot of losses in his life and doesn't want Naruto to go through the same. He knows how cruel the world can be to a ninja, especially one with Naruto's special status, so he becomes overprotective to prevent Naruto from facing similar tragedies.
Love is also a big factor. Minato loves Naruto deeply and doesn't want to see him get hurt. He has seen the harshness of the ninja world and wants to shield Naruto from all the pain and danger that comes with it. He may think that as Naruto's father, it's his duty to keep Naruto safe at all costs.
One reason could be guilt. Since Minato wasn't there for Naruto when he was growing up in the original story, in the fanfiction, he might be overcompensating for that lost time. He feels like he has to make up for all those years he wasn't around to protect his son.
Well, Minato might constantly be by Naruto's side in the fanfiction. He could prevent Naruto from taking on any dangerous missions, even if Naruto is capable. For example, he may interfere when Naruto tries to join a risky battle against a powerful enemy, saying it's too dangerous for him.
One possible reason could be for Naruto's protection. Maybe Minato knew of some great danger that was coming for Naruto and he thought that banishing him would keep him out of harm's way. Another reason might be related to some prophecy or hidden power within Naruto that Minato feared could be misused if Naruto stayed in the village.
Well, in the fanfiction world, Minato might be overprotective of fem Naruto because he lost her once. Maybe there was some kind of incident in the past where Naruto was in great danger or even 'died' briefly. This made Minato extremely paranoid about losing her again, so he goes overboard with the protection. He might also be influenced by the fact that as a female in their world, Naruto could face different and perhaps more complex challenges than if she were male, like discrimination or special treatment from certain groups.
It could be that Naruto is trying to prove himself. He wants to show that he can be as great a fighter as his father. Also, he might have received some training or knowledge transfer from someone who knew Minato well. This could have inspired him to adopt Minato's fighting style. He may also be in a situation where his normal fighting style isn't working, so he turns to Minato's as a last resort.
One possible reason could be fear. If Naruto was 'godlike' in this fanfiction, his power might be uncontrollable and Minato, as Hokage, might feel it's a threat to the village. He could think that Naruto's power could attract too many dangerous enemies or cause destruction accidentally.
One possible reason could be that Naruto discovers some long - hidden secrets about Minato that he feels betrayed by. For example, if he found out Minato had made a deal that affected Naruto's life negatively in some way, like with the Kyuubi. Maybe Naruto feels that Minato sacrificed him for the greater good of the village without really considering his future or feelings.
It might be due to jealousy. If Minato was getting more attention or praise in the village for his achievements while Kushina felt overlooked, that could create resentment. Say, Minato was constantly being hailed as a hero for his speed and battle tactics, and Kushina, who also had great power, felt like she was in his shadow.
Well, perhaps the writer wants to break the mold of the traditional Naruto story. In the original, Minato is a great father figure, but in this fanfiction concept, the writer might be aiming to show how an alternate reality could shape Naruto. Maybe they want to explore themes of trauma and how Naruto could overcome it. Or it could be a way to experiment with different character dynamics, seeing how Naruto would interact with a Minato who is not the loving father we expect. It could also be a form of creative exploration of the characters' personalities, pushing the boundaries of what we think we know about them.
One reason could be that Minato has some unfinished business with Naruto. Maybe he wants to pass on some crucial ninja skills or knowledge that only he can teach. Another reason might be the strong father - son bond. Despite being separated for so long, Minato's love for Naruto is still very deep.
It can add a lot of tension to the story. For example, Naruto might feel suffocated by Minato's overprotectiveness and constantly try to break free. This can create a conflict between them. Also, it can limit Naruto's growth as a character in some ways. If Minato is always shielding her from danger, she might not get the chance to fully develop her skills and become stronger on her own.