I think a younger version of Fleur Delacour could be an interesting character for a younger girl in the fanfiction. Fleur was very confident, beautiful, and had a certain elegance about her. A younger girl modeled after her could bring a different kind of charm to the story. Or the girl could be a new character altogether, perhaps a young witch from a far - off land who has her own set of magical skills and a curious nature, which would make her a great addition to the Harry Potter world in the fanfiction.
Well, the girl could be a very talented young witch who is a bit of an outcast among her peers because she's so young but so powerful. Harry notices her and they start to practice magic together in secret. They could form a special bond over their shared love of magic and a desire to use it for good. Maybe they end up finding a hidden chamber in Hogwarts that contains ancient spells, and they have to work together to protect these spells from falling into the wrong hands.
The girl might be a descendant of an old wizarding family that has fallen on hard times. Harry adopts her to revive the family's honor. She could have some special knowledge or heirloom that attracts Harry's attention and makes him decide to take her in.
It could be Ginny Weasley. Since they have a relationship in the original series, it's not too far - fetched to imagine a scenario where she gets pregnant. Maybe they got carried away during a time of peace in the wizarding world.
It could be quite an interesting experience. The younger girl might bring a fresh perspective. For example, she could introduce new games or ways of having fun that older babysitters might not think of. She may also be more eager to please and really put in effort to make the time enjoyable.
She could be a young girl who has lost her parents in a magical accident. Maybe she has some special powers that Harry notices and that's why he decides to adopt her.
Well, one possible plot is that the younger sister is a target of the dark forces because of her relation to Harry. She has to constantly prove herself and fight against the stigma. She could form a secret club within Hogwarts to train students in self - defense against the dark arts in a more creative way than what Umbridge allowed. And she might also have a magical pet that is not common, like a miniature phoenix.
The Shafiq girl could be a transfer student from another wizarding school. She comes from a family with a long history in the wizarding world but has a different upbringing. This gives her a unique perspective when she enters Hogwarts and meets Harry Potter. She might bring with her new magical techniques or knowledge that catches Harry's attention.
Often, they are shown as being brave, much like Harry. Since they grow up in his shadow, they might feel the need to prove themselves. So, they inherit that Gryffindor - like courage. For example, they could be the first to stand up against a bully at Hogwarts.
Maybe it's a jealous classmate. Someone who is envious of Harry's fame and power. This person discovers a dark spell that forces Harry to be a girl, thinking that it will make Harry lose his status among his friends and in the wizarding community at large. They then watch from the sidelines as Harry struggles with this new identity.
She might be an old friend of Harry's from his childhood in the Muggle world that he didn't know was a witch. She had been suppressing her magic for a long time and fainted when it finally burst out uncontrollably. Harry wakes her up and helps her understand and control her new - found powers.