What could be the reasons why Naruto is locked in his house in fanfiction?

One possible reason could be for Naruto's protection. His father might think that by locking him away, he can keep Naruto safe from the many threats in the Naruto world, like powerful enemies who might target Naruto for his special powers.

One reason could be that some in the village feared his potential as the Jinchuriki of the Nine - Tails. They might have thought locking him away would prevent him from causing chaos. Another reason could be related to those who still held grudges against the Fourth Hokage for sealing the Nine - Tails in Naruto. They took it out on Naruto by imprisoning him.

Naruto might initially be angry and shout for someone to let him out. He has a strong will and doesn't like being confined. But as time goes on, he could become more creative. He might start to communicate with his friends secretly through some ninja means, like sending messages via small animals. He would also likely be thinking about how to prove his innocence if that's the reason for his confinement. He's not the type to just sit around and accept an unjust situation.

One reason could be the fear of losing his friends. Naruto has always been very protective of his comrades. In some fanfictions, he might face a situation where he is on the verge of losing them, like a powerful enemy threatening to kill them all. This would make him afraid as his friends are his most precious things.

Perhaps in the fanfiction world, there is some sort of magical or technological device that mutes Naruto. This could be part of a plot where an enemy uses this device to stop Naruto from using his inspiring speeches or to isolate him from his friends. By muting him, they can disrupt his normal way of communicating and leading, which is a key aspect of his character.

One possible reason could be a misinterpretation of family dynamics. Maybe in the fanfiction, the author portrays Naruto's family in a way that he sees as unfair or unloving. For example, if they are shown as neglecting him or putting too much pressure on him.

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 the fanfiction, it might be that Naruto had different ideals and goals from his family. His strong will to pursue his own path of becoming Hokage, for example, could clash with the family's expectations, causing him to reject them.

It could be for strategic reasons. In the world of ninjas, showing too much emotion can be a weakness. Naruto might think that by sealing his emotions, he can become a more effective ninja and better protect his village.

Perhaps Naruto has some unresolved issues from his past that he doesn't want to burden his family with. He may think that leaving is the best way to deal with these issues on his own, without putting his family in the middle of his personal turmoil. He might go off on a solo adventure to find himself and come to terms with his inner demons.