Perhaps there is a misunderstanding between Harry and Ron regarding Hermione. Ron might say or do something that makes Harry think he's being unfair to Hermione. Since Grimmauld Place is a sort of safe haven for them all, Harry kicks Ron out in anger to protect Hermione's feelings and their group's harmony.
It could be that Ron has done something to endanger the secrecy of Grimmauld Place or the safety of the people there. Harry, being responsible for the place at that moment, decides to kick Ron out. Say Ron accidentally reveals some important information to a suspicious character, and Harry can't risk it so he takes this drastic step.
Maybe Harry has a big fight with Ron over something like Ron's lack of trust. For example, if Ron doubts Harry's intentions again as he did in the original story. Harry, in a fit of anger, kicks Ron out of Grimmauld Place.
It could be that there is no traditional 'antagonist' in the sense. Maybe it's just the situation and the conflict between Harry and Ron's personalities. But if we had to consider one, it could be an outside force that is influencing Ron's actions and making Harry distrust him. For example, a new dark magic object that is affecting Ron's judgment.
Well, perhaps Harry is angry because of some injustice he faced at Hogwarts. When he arrives at Grimmauld Place, he might find some secrets about the Order of the Phoenix that further fuel his anger. He could also have an argument with some of the residents there, like Sirius or Mrs. Weasley.
Well, perhaps Harry Potter has grown frustrated with the Order's methods. Maybe he feels that they are too cautious or not taking enough risks in the fight against Voldemort. So, he decides to break away and form his own group with a more aggressive approach to dealing with the dark forces.
Well, the plot could involve Harry exploring the secrets of Grimmauld Place on his own. Maybe he discovers hidden rooms filled with old Black family magic items. He might also struggle with feelings of loneliness and isolation, but at the same time, use the solitude to practice his magic without distractions.
One possible reason could be that in the fanfiction, the wizarding community in England has turned against Harry due to some false accusations. Maybe a powerful dark wizard has framed him for a series of heinous crimes, and the public, being misled, forces him to leave. Another reason might be political intrigue within the Ministry of Magic. There could be a new regime that sees Harry as a threat to their power and thus kicks him out.
Well, in fanfiction, it could be that when Harry arrives at Grimmauld Place, he discovers new secrets about the Black family. There could be hidden rooms or magical artifacts that are crucial to the fight against Voldemort. Maybe he stumbles upon a diary of one of the Black ancestors that reveals a long - forgotten spell or prophecy.
Well, self - discovery is a theme that pops up a lot. While at Grimmauld Place, Ron and Hermione often learn more about themselves as individuals. This in turn affects their relationship with each other. Another theme is the exploration of magic in a different context. Grimmauld Place has its own unique magical properties, and fanfictions like to play with how Ron and Hermione interact with this magic, whether it's using it to solve problems or just being in awe of it. And of course, the theme of love and friendship is ever - present, as they support each other through all the challenges the place presents.
Well, it could be about Hermione getting caught in the rain while at Grimmauld Place and then having to deal with being soaked. Maybe she has to quickly find a way to dry off and in the process, there are some interesting interactions with the other characters who are also at Grimmauld Place.
In the fanfiction, Abuela may be under a lot of pressure to keep the family's magic and reputation intact. When something goes wrong that she blames on Mirabel, she kicks her out. Mirabel then has to face the outside world alone. She could encounter various challenges and adventures, which in turn make her grow. Eventually, she might find a way to reconcile with her family and even help save the family's magic in a new way.
He will most likely meet Sirius Black. Sirius is an important figure in Harry's life and his presence at Grimmauld Place is quite significant. They could have a deep conversation about Harry's anger and what to do next.