Who could be the main antagonist in 'percy is an assassin fanfiction'?

An ancient and forgotten god who has been awakened. This god could be angry at the modern demigods for ignoring the old ways and decides to send assassins after Percy as a warning to the rest. They might want to bring back the old order where gods were feared and worshiped more and see Percy as a symbol of the new, more independent demigods.

A powerful sorcerer from another realm who uses assassins as tools. This sorcerer could see Percy as a threat to their plans of taking over the demigod world. They send their best assassins after Percy and also try to manipulate other demigods against him. They are extremely cunning and have a vast array of dark magic at their disposal.

It could be the warden of the prison. The warden might be a cruel and power - hungry person who wants to keep Percy imprisoned for his own reasons, like getting some sort of reward or power from those who put Percy there.

It could be the leader of the group that the assassin belongs to. They might be using the assassin for their own dark purposes and be the main force behind any evil plans.

It could be another powerful kitsune who wants to use the assassin for their own evil plans. This other kitsune might be jealous of the assassin's skills and wants to control them.

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.

It could be a power - hungry Atlantean noble who wants to rule not just Atlantis but also the surface world. He sees Percy as a threat to his plans and tries to stop him at every turn.

Another option is a group of anti - magic fanatics. They view Percy's wings as an abomination because they are a result of magic. They hunt Percy down, believing that by getting rid of him and his wings, they are protecting the world from the 'evils' of magic.

It could be a character who wants to use Percy - turned - Aku for their own evil purposes. Maybe a dark wizard who thinks that Aku - Percy can be the ultimate weapon to take over the world. This wizard would try to manipulate Percy's new form and powers to do his bidding.

A new and powerful demon that has emerged from the darkest corners of the underworld. This demon is bent on using Percy's connection to the overworld to break through the barriers between the two worlds and unleash chaos. It has powers that are different from what Percy has faced before, like the ability to manipulate the very essence of the underworld's environment.