Their parents' old friends could be main characters. They might come to check on Harry and his sister, bringing gifts and stories about their parents. These friends could offer guidance and protection when needed.
The sister might have her own group of friends in the wizarding world. When she takes in Harry, she brings him into this circle. They all contribute to his upbringing. For example, one friend could be a potions expert and teach Harry about potions in a fun way. Another could be a great dueler and train Harry in combat magic. His sister coordinates all this, ensuring Harry gets a well - rounded magical education and a loving family environment.
Voldemort's remaining followers could be antagonists. They might target Harry's little sister thinking they can use her to get to Harry. They could try to kidnap her or use dark magic on her.
In a 'Harry Potter and His Little Sister' fanfiction, the sister could be a new student at Hogwarts when Harry is in his later years. She struggles to fit in because of being Harry Potter's sister. Harry has to help her deal with the pressure, make friends, and also face the threat of a new dark wizard who has a vendetta against the Potter family.
One possible plot could be that his grandfather, perhaps a powerful but reclusive wizard, trains Harry in unique magic from a young age. Harry might grow up with a different set of values and skills compared to the original story. He could have a closer bond with the wizarding world's older traditions.
In fanfiction where Harry Potter is raised by his fans, the plot could involve a lot of interesting scenarios. For example, he might be exposed to a much more modern and diverse view of the wizarding world from the start. Fans could introduce him to different magical cultures that were not fully explored in the original books. He might also grow up with a stronger sense of self - worth as fans would likely shower him with love and support, which could make him more confident in his abilities.
One common theme is family. Since it's about Harry having a little sister, it often explores the family dynamic. How they support each other, protect one another, and sometimes even have sibling rivalries. Another theme is identity. The little sister has to figure out who she is in the shadow of her famous brother.
Well, in fanfiction about Harry Potter having a little goblin friend, it could be really interesting. Maybe the goblin friend is an outcast in the goblin society and Harry befriends him. They might go on adventures together in the Forbidden Forest, looking for rare magical plants. The goblin could have special knowledge about the forest that Harry doesn't. And they could also form an alliance against the Death Eaters or other threats in the wizarding world. It would add a whole new dimension to Harry's experiences in Hogwarts and beyond.
One possible reason could be jealousy. Maybe the sister is getting more attention from their parents or at Hogwarts. For example, if she is a star student and Harry feels overshadowed.
The plot would change drastically. Harry would not be living with the Dursleys, so there would be no need for him to escape that horrible situation. Voldemort might have a harder time targeting him as his parents would be on high alert. There would be no letter - hunting drama. Also, his relationship with Snape would be different as his father was Snape's rival. His parents could have taught him some advanced magic from a young age, which would make him stand out at Hogwarts in a different way than in the original story.