Who could be the main villain in 'Harry Potter Saves the Goblin King' fanfiction?

It could be a dark wizard who has a vendetta against goblins. This wizard might see goblins as a source of power or wealth and wants to enslave them. So when Harry tries to save the goblin, this dark wizard becomes the main obstacle.

It could be that the Goblin King's magical artifacts are being stolen one by one, and this is weakening his realm. Harry Potter gets wind of this and decides to help. He teams up with some of his Hogwarts friends like Hermione and Ron. They use their combined knowledge of magic and spells to track down the thieves and return the artifacts to the Goblin King, thus saving his kingdom.

It could be Voldemort. Imagine if Voldemort somehow extended his reach into the world where Elia Martell is. His thirst for power and domination could lead him to target Elia for some reason. Harry, having already fought Voldemort in his own world, would be the perfect hero to stop him from harming Elia.

A group of dark creatures like Dementors could be the antagonists. They might be after the young goblin because goblins have a unique life force that can sustain Dementors in a way other prey cannot. Harry Potter would have to face his own fears while using powerful Patronus magic to drive the Dementors away and save the goblin.

Maybe Magneto could be the villain in a sense. He could have a misunderstanding about Harry and think he's a threat to mutants. So he attacks Xavier's Mansion while Harry is there, and Harry has to convince Magneto that he's there to help and not harm mutants. And there could be a more powerful dark force manipulating Magneto from behind the scenes.

Well, perhaps Harry stumbles upon a goblin in a dangerous situation, like being trapped by dark wizards who want to steal the goblin's magic artifacts. Harry uses his skills and spells to fend off the bad guys and rescue the goblin.

The Goblin King could interact with Hermione by challenging her intellect. For example, he might present her with a complex riddle related to goblin lore that she has to solve. With Ron, he could have an argument over food or some valuable item that Ron accidentally took from a goblin - owned place. And with Neville, the Goblin King might initially underestimate him but later be impressed by Neville's courage when they face a common threat together.

Well, perhaps the young goblin is in danger from some dark wizards who want to use its unique magical abilities for evil. Harry Potter, being the hero he is, stumbles upon the situation and uses his skills and magic to fend off the bad guys and save the goblin. Maybe he discovers the goblin has some information crucial to the wizarding world's safety too.

Well, maybe the goblin child is in danger because of some dark wizards who want to use the goblin's skills for evil. Harry Potter stumbles upon this situation and decides to protect the child. He could use his magic skills like the Patronus charm to fend off the dark wizards and then find a safe place for the goblin child, perhaps among the friendly goblins in Gringotts.

It could be a new character created by the fanfiction author. Maybe a powerful wizard who was once shunned by the wizarding community and now wants revenge by stealing magic.