One possible plotline could be Harry finding new and unexpected allies outside of the wizarding world he once knew. Maybe he discovers a hidden community of magical beings who are shunned by the mainstream wizarding society and they take him in.
In some 'Harry Potter Gets Disowned' fanfictions, there could be a plot where Harry uncovers dark secrets about his family that led to his disownment. This discovery could be a turning point, making him question everything he thought he knew about his family history, magic, and his place in the wizarding world. It might also drive him to seek revenge or justice against those who wronged him or hid the truth from him.
One plotline could be Harry finding a new family among his friends at Hogwarts. They become his support system and help him grow in ways his biological parents couldn't. Another could be Harry's journey to discover why his parents disowned him and uncovering some dark family secret along the way.
One interesting plotline could be that Harry wishes for the return of his parents. This would completely change the dynamic of the story. He would no longer be an orphan and would have a family to support him. It might also change his relationship with Dumbledore, as he wouldn't be as dependent on the headmaster. Another could be that he wishes for an end to Voldemort without having to fight. This would lead to a very different kind of resolution to the main conflict in the series.
One interesting plotline could be Harry getting help from a secret magical society that has been hidden from the wizarding world. This society might have unique spells and knowledge that they share with Harry to defeat Voldemort.
In some fanfiction, Harry might get married in a secret ceremony to protect his family from a new threat. His friends would be the only ones in on the secret. The wedding could take place in a hidden location, like an ancient, enchanted forest. His wife could be a powerful witch who has her own secrets. Their marriage could be a key part of a bigger plan to defeat an emerging evil. There could be a lot of mystery and intrigue surrounding their relationship, with them having to keep their true feelings and intentions hidden from the outside world.
One interesting plotline could be Harry exploring the full extent of the Elder Wand's power without being corrupted by it. He might use it to restore parts of the wizarding world damaged during the war.
One interesting story could be where Harry is disowned by the wizarding world after being wrongly accused of a dark magic crime. In this fanfiction, he has to find his own path outside of the traditional magical society, relying on his own wits and the few friends who still believe in him.
A plotline could involve them discovering new magical abilities or powers as a result of this trauma. It's possible that the emotional upheaval of being disowned unlocks latent magic within them. They could then use these new powers to not only better their own situation but also to help other outcasts in the wizarding world. Maybe they start a secret group for those who have been rejected by their families.
Hermione is often a key character. She might stand by Harry's side, using her intelligence and loyalty to help him through the tough times. She could be the one to encourage him to keep going and not let the disownment break him.
One possible plotline could be that Harry gets grounded for accidentally using magic outside of school in a Muggle area. This might lead to him having to deal with the disappointment of his friends who can't visit him as easily. Another could be that he gets grounded because he was caught sneaking out to follow a lead on a new dark wizard threat, and the adults in his life want to keep him safe by restricting his movements.
Some fanfictions might have Harry getting revenge on the Ministry of Magic for their incompetence and corruption. He could expose their wrongdoings to the wizarding public and bring about a new era of transparency and fairness in the magical government.