Who would be the main antagonist in a 'Percy meets Aphrodite' fanfiction?

Perhaps a rogue group of mermaids and mermen. They don't like the idea of Triton allying with Percy, a half - blood. They believe that Triton should only focus on the pure - blooded sea creatures. So they become the main antagonists, constantly attacking Percy and trying to turn Triton against him.

It could be a new monster that is after Percy. Since Percy is a demigod, there are always monsters chasing him. This new monster might be something that Paul has never seen before and it could put both of them in danger.

A possible main antagonist could be Eris, the goddess of strife. She might be jealous of Aphrodite's beauty and power and see Percy as a tool to disrupt Aphrodite's plans. Eris could send her minions to create chaos and conflict between Percy and Aphrodite, trying to make them turn against each other.

It could be a new monster that is specifically targeting Percy's mortal connections, like Paul. Maybe a monster that feeds on the fear of mortals who are close to demigods.

Maybe a group of mercenaries who are also interested in the valuable artifacts related to Greek mythology. They would be willing to do anything to get their hands on them, and they are a threat not only because of their weapons but also because they have some knowledge of the ancient secrets that could be used against Percy and Lara. They could set up ambushes and try to steal the artifacts from Percy and Lara while they are in the middle of their exploration.

A group of rogue demigods could be the antagonists. They are jealous of Percy and Jason's fame and power. They form a secret alliance and start causing trouble for the other demigods. Percy and Jason meet while trying to figure out who is behind these attacks. At first, they suspect each other, but then they realize the real culprits are this group of rogue demigods and join forces to stop them.

It could be an ancient sea creature that was once imprisoned by Amphitrite and Poseidon. Now that Percy has come into the picture, it senses an opportunity to break free. It uses its dark powers to manipulate the ocean and turn it against Percy and Amphitrite, hoping to create enough chaos to shatter the chains that bind it once again.

Maybe a rogue ninja who has somehow tapped into dark powers related to Kami's domain. This ninja wants to use these powers to take over the ninja world, and Naruto, with Kami's help, has to stop him. In this fanfiction, the rogue ninja could have some personal vendetta against Kami as well, which adds more depth to the story.

There's a possibility that an evil scientist from another planet could be the main antagonist. This scientist wants to use Bulma's knowledge and Cell's power for his own evil experiments. So he tries to break up their partnership and capture them both for his own purposes. He sends his minions after them and creates various obstacles for Cell and Bulma to overcome.

It might not be so straightforward. While Esdeath has the potential to be the antagonist, there could be other forces at play. For example, there could be a third party that is manipulating both Tatsumi and Esdeath for their own gain. In this case, both Tatsumi and Esdeath could be seen as victims of this greater evil, and they might have to team up against this new threat. However, if we consider the traditional view, Esdeath's actions and beliefs are in direct conflict with Tatsumi's, so she remains the likely antagonist.