The Weasley family would probably play a role too. Ginny could be a role model for the little sister, especially in terms of being a strong female witch. Fred and George might teach her some of their pranks or tricks. And Mrs. Weasley could be like a second mother to her, showing her the warmth of a family. The Malfoys could also be in the story, perhaps as antagonists, creating conflict for the little sister and Harry.
One interesting plotline could be the little sister discovering she has her own unique magical abilities that are different from Harry's. For example, she might be able to communicate with magical creatures in a way no one else can.
One idea could be that Harry's little sister has a unique magical ability that no one else in the family has. For example, she might be able to communicate with magical creatures in a way that even Hagrid is impressed by. This could lead to all sorts of adventures where she helps solve problems in the wizarding world using this special skill.
Well, they could have a protective relationship. Draco might be very protective of his little sister, shielding her from the darker aspects of the wizarding world he's involved in. For example, if there are threats from other wizarding families or the general chaos in the world, he'd stand up for her.
She could be a half - blood like Harry. Maybe her mother was a muggle - born witch and her father was a pure - blood wizard. This mixed heritage could give her a unique perspective on the wizarding world's issues regarding blood purity.
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.
Another theme is the little sister getting caught up in the world of fame through Harry. Maybe she starts getting followed by paparazzi just because she's related to him. It adds an interesting dynamic as she has to deal with this new aspect of her life.
Yes, there are quite a few. Some explore how a sister would change the dynamic of Harry's family and his adventures at Hogwarts. For example, she might be an additional source of support for Harry or have her own unique magical abilities that come into play during the fight against Voldemort.
Obviously, Sherlock himself is a very popular character. His brilliant mind and unique personality are central to the fanfiction. The little sister, of course, is also a key figure. Depending on how she's written, she can be a strong, intelligent character in her own right.
One possible plot could be that Naruto's little sister is also a ninja in training. She might struggle with the same kind of ostracism Naruto faced because of the Nine - Tails inside him. However, she could also be a source of great support for Naruto, helping him through his toughest times and together they could train to become stronger. Maybe she has a unique ninja ability that even Naruto is in awe of.