What could be the plot of 'Harry Potter Exiled from Gryffindor' fanfiction?

One possible reason could be a false accusation of using dark magic. In some fanfictions, the wizarding world can be very paranoid about dark magic, and if Harry was wrongly suspected of delving into it, Gryffindor might exile him to protect their reputation.

A dark force that has the ability to influence the minds of Gryffindor members. This could be a powerful and ancient magic or a new form of dark magic. It turns the house against Harry without them fully realizing it, making the collective Gryffindor house, under this influence, seem like the antagonist.

He would probably be extremely hurt. Gryffindor was like his family at Hogwarts, so being exiled would be a huge blow. He might initially feel angry and betrayed.

In a 'Harry Potter betrayed by Gryffindor' fanfiction, perhaps there is a prophecy that is misinterpreted. The Gryffindors think Harry is the cause of upcoming doom instead of the savior. So, they begin to betray him. Harry would then have to struggle not only with the external dark forces but also with the internal pain of being rejected by those he considered friends and housemates. He might start to question his own identity and values, and his journey would be about regaining the trust of Gryffindor or finding his own path without them.

Well, it could be that there's a misunderstanding. Maybe some Gryffindor students think Harry has done something wrong, like he's been framed for a crime in Hogwarts. So they turn against him in anger and attack him. But later they find out the truth and feel really guilty.

Well, it could be about Harry struggling to fit in with the typically bold Gryffindors. Maybe he has a hard time speaking up in class or during Quidditch matches. He might have a small group of close friends who help him come out of his shell.

There could be many reasons. Maybe some fanfiction writers want to create an alternate universe where Harry has a different path. It could also be for the sake of creating a more complex and unexpected plot, like having him be falsely accused of something so bad that Gryffindor doesn't want him. Another possibility is that the writer wants to explore how Harry would react and grow outside of the Gryffindor environment he's so closely associated with in the original series.

One possible reason could be a fallout with his friends in Gryffindor. Maybe he feels betrayed by them in some way in the fanfiction world. For example, if they wrongly suspect him of something.

Perhaps he leaves Gryffindor in fanfiction because he is influenced by a new mentor or friend who is from a different house or group. This person might convince him that he can achieve more or be more true to himself outside of Gryffindor. Also, it could be due to a prophecy or a special mission that requires him to distance himself from Gryffindor for a while to protect the house or the entire Hogwarts from a certain threat.

In some fanfictions, it could be a political move within Hogwarts. There might be a group that wants to undermine Dumbledore's influence, and since Harry is so closely associated with him, they target Harry by getting him banished from Gryffindor. This could also be related to the discovery of some long - hidden secret about Harry's family that makes the Gryffindors view him differently.