In some fanfictions, it could be an original character created by the author. Maybe a witch who was the result of an affair that his father had before he married his mother. However, this is completely against the canon of the original books, but in the world of fanfiction, anything is possible.
Sure. In the world of fanfiction, all kinds of alternate universes are created. A story where Ginny is Harry's sister could be really interesting. It might change the romantic aspect between them that exists in the original series. Instead, they could have a more sibling - like bond, protecting each other in a different way and having a whole new set of family - related storylines.
Yes, there might be. The 'Supernatural' world of Sam and Dean and the 'Harry Potter' universe are both very popular, and fanfiction often likes to cross over different fandoms in creative ways. Some fans might have come up with the idea of making Harry Potter be related to Sam and Dean as their sister in a fan - created story.
In some fanfictions, it could be through powerful magic spells that he discovers or is taught. Maybe he stumbles upon an ancient spell in the restricted section of the library that allows him to summon a family member. Another possibility is that he unknowingly activates some kind of magical artifact that has the power to bring a sister into his life.
She could develop her identity through her relationships. For example, making friends at Hogwarts who see her as an individual, not just as Harry Potter's sister. She might join a club or a study group where she can shine on her own merits.
Another idea for a fanfiction could be that Fleur Delacour's sister is a powerful witch in her own right but has a completely different approach to magic. While Fleur is all about grace and charm in her magic, her sister might be more into dark arts - not in an evil way, but in a way of studying it to understand how to combat it better. She could end up teaming up with the Trio (Harry, Ron, and Hermione) to fight against a new dark wizard threat at Hogwarts.
One common theme is family loyalty. Since they are siblings, the stories often focus on how they support and protect each other. Another theme is the discovery of self. The sister, who may have been hidden or in the background, often has to figure out who she is in relation to Harry and the wizarding world. Also, the theme of facing challenges together is prevalent. They join forces to take on the threats in the wizarding world, just like Harry did with his friends in the original series.
Sister Lemon is a fictional character created specifically for this fanfiction. She doesn't exist in the original Harry Potter series. She's likely a character designed by the fanfiction writer to add a new element to the well - known wizarding world of Harry Potter.
There could be various storylines involving Heather as an older sister in Harry Potter fanfiction. Maybe she's a Gryffindor like Harry and helps him out in his adventures, or she could be a Slytherin with her own complex motives.
In such fanfiction, it could lead to a whole new dynamic within the wizarding world. Maybe she'd have her own unique powers or play a crucial role in Harry's adventures.