It could be some of the Slytherin students who have a long - standing enmity with Harry in the original story. They might be acting on their own or be influenced by some darker forces in the fan - fiction.
Perhaps a new character introduced in the fan - fiction. This new character could have a hidden agenda against Harry. Maybe they come from a family with a grudge against Harry's family or they are working for an enemy of Harry's. For example, if there was a new dark wizard family that emerged in the fan - fiction world and they saw Harry as a threat to their rise to power.
There's also a chance that it was someone under the Imperius Curse. In the wizarding world, this curse can make people do things against their will. So, it could be an innocent - looking character who was actually being controlled by a more sinister figure to beat Harry in the corridor.
Well, one possible reason could be that he was targeted by some rival students or a dark magic group within the fan - fiction world. Maybe they were jealous of his abilities or had some vendetta against him.
Perhaps it's an older wizard who has been collecting stories about the great house - elves in the wizarding world for a long time. Dobby, being such a well - known and beloved elf, became the focus of this particular fan fiction. This author might have a deep knowledge of the history of house - elves and used that to create a rich backstory in the fan fiction.
Relatives with a claim to the throne might be suspects. They could have been impatient to take over. They might have arranged for the king's death and then, fearing the queen's influence or her own claim to the throne, got rid of her as well.
Perhaps it's a new dark creature that has emerged in the Black Lake. This creature sees Harry as an easy target and takes him hostage, either for food or for some other unknown reason. It could be that this creature has some sort of grudge against humans or wizards in particular.
There could be a new character introduced, perhaps an old family friend or a long - lost relative that the potion reveals. This character could have a wealth of knowledge about Harry's family history and help him navigate the new world of understanding his parentage. Additionally, Voldemort might still be relevant. If the potion shows some connection between Harry and Voldemort's family or past, it could add a whole new layer to their relationship and the overarching story of good versus evil in the fan fiction.
Definitely the Giants. They have a history of causing trouble for the demigods. Annabeth's disappearance could be part of their plan to weaken the demigod forces. They might think that without Annabeth, the demigods would be less organized in their battles.
It could be Ginny. Since Ginny has had a long - standing relationship with Harry in the original series, it would make sense for her to be the main love interest in this fan fiction as well. Maybe Harry is brewing the soulmate potion to reaffirm their connection.
Fans of the original work that Harry is from might be interested. They could be curious to see an alternate take on his character, even if it's a rather unflattering one like this 'whore' concept. It could also attract those who like exploring the darker or more controversial sides of a character.
There could be a rogue ninja hiding in the cave. This ninja might be on the run from the authorities and has some secrets that Naruto is interested in. Maybe they end up teaming up for a while.
It could be Draco. In some fan fictions, they have a complex relationship that could develop into a romantic interest. Draco's character has a certain allure and his past enmity with Harry could transform into a deep, passionate love in the context of a gay fan fiction.