Who could be the main antagonists in 'Harry Potter and Percy Jackson mates fanfiction'?

In this fanfiction, Voldemort or his remaining followers could be major antagonists. They wouldn't like the idea of Harry having new allies in Percy and the demigod community. From the Percy Jackson side, the Titans or some of the more malevolent gods might not be happy with the alliance either. They could try to break it up or cause trouble for the two boys, seeing them as a potential force against their own plans.

Another option could be a group of rogue demigods who have turned to the dark side. They follow Percy to Forks, hoping to find some powerful artifacts there. They don't care about the vampires or werewolves and are willing to cause destruction to get what they want. Percy has to stop them while also dealing with the local supernatural creatures.

The Giants might also be antagonists. They could band together and target Percy's kingdom, believing that by destroying him and his rule, they can undermine the power of the gods further. They might use their brute strength and strategic thinking to attack Percy from different fronts.

In some fanfictions, Voldemort or his remaining Death Eaters could still be the main antagonists. They might target Harry and Neville specifically because they see them as a threat to their plans of taking over the wizarding world again.

It could be a rogue Death Eater who escaped the clutches of justice after Voldemort's fall. This Death Eater might be seeking revenge on Harry and decides to target Bill as well since he's Harry's mate.

The main antagonists could be the Titans. They are powerful enemies in the Percy Jackson universe already. Now that Percy has Superman - like powers, they might see him as an even greater threat to their plans of overthrowing the gods. So, they would do everything in their power to stop him.

The main antagonists could be the remaining Titans who see Percy as the last obstacle in their plan to take over the world. Since Spartans were known for their great fighting skills, the Titans would want to eliminate Percy to ensure their victory.

The Titans could still be a major threat. Since Percy is now the Host of Chaos, they might see him as a new opportunity to regain power. Kronos could try to manipulate Percy's chaotic powers for his own gain, or maybe use Percy's new status to cause more chaos in the world and then step in to 'restore order' in a way that benefits the Titans.

The Titans might still be a threat. Even though they were defeated before, they could have some remnants or followers who don't want Percy to become an Olympian because it would strengthen the Olympian side even more.

The Titans could be great antagonists. They might see Percy as a threat to their plans of regaining power. Since he has the power of Aether, they could fear that he'll be able to stop them in ways other demigods can't. Another option could be some dark demigods who are jealous of Percy's connection to Aether and want to steal his powers for themselves.