Who could be the main antagonists in 'percy adopts sallys daughter fanfiction'?

In this fanfiction, the plot could involve Percy initially being hesitant to adopt Sally's daughter. But as he gets to know her, he realizes she has a lot of potential and a great heart. He starts to provide for her, like getting her into a good school if it's a modern - setting story. And they could go on adventures together, facing challenges that strengthen their bond.

She could be a completely new character created just for this fanfiction. Maybe she's a normal human girl who Percy discovers has a connection to the world of the gods in some way.

She could be the daughter of a minor god that has been forgotten or shunned. For example, the daughter of Hecate's lesser - known cousin who has some magic abilities but no real place in the demigod world until Percy takes her in.

Maybe some of the more vengeful gods could be antagonists. For example, if Hera doesn't like Percy's decision to adopt Thalia, she could send various challenges their way. Also, there could be some ancient monsters that are awakened by Thalia's presence, and they would want to destroy her. These monsters could be sent by some minor gods who are jealous of the attention Thalia might get from the major gods.

In the Naruto world, it could be Orochimaru. He might be interested in Naruto's newfound Pokémon - related powers and try to capture him to experiment on him. Orochimaru is always after power, and Naruto's unique abilities could be very appealing to him.

Another possibility is that some rogue ninja who have a vendetta against Hanzo might target Naruto as a way to get back at Hanzo. They could see Naruto as Hanzo's weakness and try to harm or kidnap him, which would then lead to a series of battles and confrontations in the fanfiction.

The main antagonists could be the traditional enemies of Camelot like Morgana. She might see Merlin's act of adopting Mordred as a threat to her plans. Also, some of the knights or nobles in Camelot who are superstitious and believe Mordred is a danger just because of the prophecies could be antagonists. They might try to separate Merlin and Mordred or even harm Mordred.

Some of the old monsters from Greek mythology that have a vendetta against Aphrodite's lineage could be the main antagonists. Maybe a spurned former lover of Aphrodite who was turned into a monster. This monster targets the daughter of Aphrodite and Percy because they are symbols of Aphrodite's power and influence. It constantly tries to harm them and thwart their plans.

The Death Eaters could still be the main antagonists. They might see Fenrir's new alliance with Harry as a threat. Since they once used Fenrir for their dark deeds, they don't want him to turn good and expose their secrets.

It could be a group of rogue ninjas from the new time period who see Jiraiya as a threat to their plans. Since he has different skills and knowledge, they might want to eliminate him.