Perhaps in the magical world, there are those who disapprove of Hermione's interest in figure skating. A strict magical authority figure could be the antagonist, trying to force Hermione to focus only on magic and give up her figure skating fanaticism. They might threaten to take away her magic or something she values if she doesn't comply.
It could be a jealous figure skater who sees Hermione getting too close to their idol or a rival skater. This person might try to sabotage Hermione's attempts to be involved in the figure skating world, like spreading false rumors about her or causing problems at the skating rink.
There could also be a dark wizard or witch who has an ulterior motive related to figure skating. Maybe they want to use the large crowds at skating events for some dark magic ritual, and Hermione, being so involved in the skating world, stands in their way. So they target her to keep her from interfering.
Maybe Fleur Delacour. She has grace and elegance, which are important qualities in a figure skating coach. She could teach Harry how to move more fluidly on the ice and give him tips on how to present himself during his performances. Her Veela charm might even give him an extra boost of confidence when he's skating in front of an audience.
One possible plotline could be Hermione attending figure skating competitions and getting inspired to write about the sport. She might meet a figure skater and become friends, and through that relationship, learn more about the dedication and hard work required in figure skating.
It could be a figure skater. Maybe a rising star in the skating world who Bella meets at a competition and they strike up a connection. He might be drawn to her passion for the sport.
Another possibility is a dark wizard or a group of dark wizards who are after some powerful magic that the Lestrange family has, and Hermione gets in their way as she tries to protect the family or uncover the secrets. They would be the main force that Hermione has to face and overcome throughout the fanfiction.
Perhaps a powerful magical being from a different realm is the antagonist. This being might mistake Hermione for someone else or see her as a key to something in the wizarding world. So, it uses its magic to make her disappear. This being would be very difficult to defeat or negotiate with, making it a huge challenge for those trying to find Hermione.
It could be a jealous wizard who wants to steal Fudge's lemon - related magic for his own glory. This wizard might try to frame Hermione for stealing it first so that he can get her out of the way.
One potential main antagonist could be a disgruntled professor. This professor might feel that Hermione is too much of a know - it - all and decides to deage her as a form of punishment. Or it could be a Death Eater who has infiltrated Hogwarts. They know that Hermione is a valuable asset to Dumbledore's side, so they deage her to weaken the opposition. The Death Eater could then use the deaged Hermione as a pawn in their evil plans.
In some cases, the antagonist could be a group of magical creatures that have been wronged by wizards in the past. They see Hermione as a representative of the wizarding world and when she is left behind, they try to make her pay for the past wrongs. These creatures could have unique powers and abilities that make them a formidable foe for Hermione.
It could be a power - hungry student who wants to undermine Hermione and Favo Prefect. This student might be jealous of their status as prefects and the respect they get from teachers and students alike. So, they try to create problems for them, like spreading false rumors or sabotaging their projects.
It could be an old and powerful vampire who sees Hermione as a threat to his rule. Since Hermione is a very intelligent witch - now vampire - she might be able to figure out a way to undermine his power.