Who could be the main antagonist in 'Artemis Fowl becomes a Fairy fanfiction'?

Perhaps Artemis, now a fairy, could use his knowledge of the human world to bridge the gap between humans and fairies in a more positive way. He could introduce human technology to the fairies, while also learning and sharing fairy magic with humans. This would create a unique story where he is sort of a cultural ambassador between the two worlds.

Perhaps a jealous classmate who discovers Artemis's connection to the fairy world. This classmate wants to use that knowledge to gain power and popularity, so they start causing trouble for Artemis and his friends, trying to expose them to the wrong people or get in the way of their fairy - related investigations.

There might be a group of anti - magic fanatics as the main antagonists. They view Natsu's new and extremely powerful magic as a danger to the natural order of the magical world. They would try to eliminate Natsu and any other powerful mages in Fairy Tail who support him, believing that magic should be limited and controlled, not allowed to reach such overpowered levels as Natsu has.

Maybe the main antagonist is an ancient evil that has awakened. It has the power to manipulate Artemis's mind, making her kidnap Percy against her will. This evil entity wants to use Percy as a sacrifice to gain more power. So, while Artemis is the one who physically kidnaps Percy, the real force behind it, the ancient evil, is the true antagonist.

Maybe a powerful warlord from Negan's world who somehow follows him into Artemis' realm. This warlord, with his own thirst for power and destruction, would oppose both Negan (if he starts to side with Artemis) and Artemis herself, wanting to take over the new world he has found.

Perhaps a powerful and corrupted demigod could be the main antagonist. This demigod might be jealous of Artemis' power and popularity among the other demigods. He devises a plan to harm her, and Percy, being loyal to Artemis, has to give his life to save her from this rogue demigod.

It could be a powerful Titan who has escaped from Tartarus and blames Artemis for something in the past. So he's out to get her, and Percy has to stop him at all costs, even if it means his death.

The Titans could also serve as antagonists. If they sense that the union of Percy and Artemis could strengthen the power of the gods, they would do everything they can to stop the marriage. They could send their minions to attack Percy and Artemis, or they could try to corrupt one of them, perhaps by offering Percy great power in exchange for abandoning Artemis, or by making Artemis believe that Percy will bring destruction to her followers if she marries him.

A powerful Titan who has escaped from Tartarus could be the main antagonist. He might be seeking revenge on Artemis for her role in the previous battles against the Titans. This Titan could have new and terrifying powers that make him a formidable foe for Percy and Artemis.

A powerful Titan who has a grudge against both Percy and the Hunters of Artemis could be a great antagonist. Maybe he wants to use the power of the Hunters for his own evil purposes or destroy Percy to get revenge on the gods.