It could be a dark wizard who wants to use Harry's sister for some dark magic purpose. Maybe he believes that her blood or her unique magical essence can be used to open a portal to a world of dark magic or to resurrect an even more powerful dark force. This antagonist would stop at nothing to get his hands on her.
In some fanfictions, Harry's sister might be sorted into a different house than him, like Slytherin. This would create a lot of internal conflict within the family as well as at Hogwarts. It could lead to a situation where Harry has to defend his sister against the prejudices of his friends. Or perhaps she has a prophecy related to her that ties into Harry's own destiny, and they have to figure out how to fulfill both prophecies without sacrificing one another.
One interesting birthday wish could be to receive a magical creature like a Hippogriff. In Harry Potter fanfiction, characters often have a deep longing for unique and dangerous magical creatures. Another wish might be to get a time - turner so they can relive certain moments or study more magic. And a third could be to be accepted into a secret and powerful magical society within Hogwarts, like the fabled Order of the Phoenix.
Birthday wishes in Harry Potter fanfiction can act as a window into a character's desires. For instance, if a character wishes for a magical item, it shows what they lack or covet in their magical life. It can also be a plot device. If a character's birthday wish is granted in an unexpected way, it can drive the story forward. Say a character wishes for courage and then is faced with a dangerous situation where they have to be brave.
A genie might grant the wish for a character to have the power of time - travel without the limitations of a Time - Turner. This would allow them to go back and forth in time freely. They could prevent certain tragedies from happening, like Sirius Black's death or Cedric Diggory's murder. This would have a huge impact on the overall plot and relationships in the story.
One interesting plotline could be the main character using their wishes to change some of the major events in the Harry Potter universe. For example, they might wish to prevent certain characters from dying. Another could be using a wish to gain a special power that helps them in their adventures at Hogwarts, like being able to communicate with magical creatures more easily.
Well, it really depends on how the author writes them, but Draco Malfoy can be a very popular character in this type of fanfiction. In some stories, the reborn character might use a wish to change Draco's personality or his family's stance in the wizarding world. This can lead to some really interesting character development for Draco. Another character could be Dumbledore. The reborn character might wish to have a different kind of relationship with Dumbledore, perhaps getting more guidance from him earlier on, and that makes Dumbledore an important and popular figure in these stories.
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.
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.