His character could become more complex. He would be dealing with feelings of betrayal and isolation. This could make him more empathetic towards those who are also outcasts in the wizarding world. He might also become more determined to prove himself. Since he was kicked out of Gryffindor, he would want to show everyone that he is still a good wizard. He could start to study magic in a different way, not following the Gryffindor - centric methods he was used to. This would lead to him developing new magical skills and a different perspective on magic as a whole.
He might become more independent. Without the support of Gryffindor, he would have to rely on himself more. He could also become more cynical. Being kicked out of his house would be a big blow to his sense of belonging.
He might seek refuge in another house. For example, he could try to convince the Hufflepuffs to take him in. The Hufflepuffs, known for their acceptance, might be his best bet. This could lead to a whole new set of relationships and storylines as he adjusts to a different house environment.
In some fanfictions, if Harry is kicked out of Gryffindor, he might end up joining another house like Hufflepuff. The Hufflepuffs are known for their acceptance and might welcome Harry with open arms. This could lead to a whole new set of adventures for Harry, as he would have to adjust to the different values and culture of Hufflepuff house.
Hermione would probably be outraged. She would immediately start investigating the situation to find out the truth. She'd be convinced that there has been some sort of mistake or foul play. She might even go as far as to confront the teachers or the Gryffindor house leaders about it.
One reason could be that he breaks a major school rule. For example, if he uses dark magic without proper authorization, the Gryffindor house might decide to expel him. Gryffindor values courage, but there are limits, and using dark magic goes against the values of the school as a whole.
Ginny could first be in shock. But then, she would start thinking of ways to help Harry. She could offer him emotional support, like being there for him when he is feeling down about being expelled. She may also try to rally their mutual friends to support Harry, whether it's by protesting the decision or by helping him find a new place to belong in the school.
If Harry was kicked out of Gryffindor in Ginny - related fanfiction, Ginny would likely be one of the first to oppose the decision. She might secretly help Harry by providing him with a place to stay in Gryffindor's common room undetected. And she could start her own investigation into what really happened, suspecting foul play. After all, Harry has been a hero in Gryffindor and Ginny wouldn't let him be cast out so easily.
Maybe he's falsely accused of stealing important Gryffindor artifacts. For instance, if the Sword of Gryffindor goes missing and Harry is wrongly blamed, the house might decide to kick him out. It could be part of a plot by a jealous student or an outside force trying to disrupt Hogwarts.
It could be due to a series of bad decisions that made him seem like a bad influence in Gryffindor. For example, if he constantly got into fights with other Gryffindors and disrupted the harmony of the house, they might kick him out. Also, if he was caught breaking too many school rules in a way that reflected poorly on Gryffindor as a whole, like sneaking out at night to go to the Forbidden Forest too often without a good reason, that could lead to his expulsion.
His character often develops a stronger sense of self - identity. Knowing he is the son of Gryffindor gives him a different perspective on his own actions and destiny. He may become more confident in his leadership abilities as he is now linked to one of the greatest wizards in Hogwarts' history.
Harry's character could become more cautious. Dealing with a succubus would make him realize that there are many dangerous and unpredictable forces in the magical world. He might also become more secretive as he doesn't want others to know about the succubus he has bound.