One interesting plot twist could be Percy having to deal with the other gods' jealousy. Since he's a new king, the old gods might not be happy with his rule. For example, Zeus might try to undermine Percy's decisions. Another could be Percy using his new powers in unexpected ways, like creating new mythical creatures. And a third could be Percy facing a threat from an outside force that the old gods couldn't handle but as king, he has to find a solution.
Well, perhaps a great plot twist is Percy realizing that being king of the gods isn't all it's cracked up to be. He might find that the power corrupts him in ways he didn't expect. He starts making decisions that go against his original values. Or maybe there's a plot twist where Percy discovers a hidden prophecy about his reign as king that changes everything. It could be that he has to sacrifice something dear to him to save the world of the gods. Also, he could face a rebellion from within the ranks of the gods who don't believe he's worthy.
Well, one plot twist could be that Percy kills the gods, but they are reborn in different forms. For example, Zeus is reborn as a young girl with all his powers intact. This would turn the whole story on its head as Percy now has to deal with these new incarnations of the gods he thought he'd defeated. And it could lead to a whole new set of adventures and challenges for him as he tries to figure out what to do with these reborn deities.
One interesting plot twist could be that Percy discovers he has a hidden connection to the father of the gods that gives him new and unexpected powers. For example, he might find out he can control a part of the godly realm that was previously unknown. This would change his role in the demigod world and make him a target for both friends and foes who want to use or stop his newfound abilities.
Another plot twist could be that Percy discovers he has some hidden power or heritage as a result of the betrayal. For instance, he might find out that he has a connection to an ancient and powerful force that the gods were afraid of, which is why they betrayed him. This new power then becomes a key element in his journey to either seek revenge or prove his worth.
One idea could be Percy having to face a new and powerful enemy that even the other gods are afraid of. He has to use his unique skills and connections to defeat it.
Well, one interesting plot could be when the main character in the fanfiction discovers some hidden powers that are related to the 'king of gods' concept. Maybe it gives them an edge in battles against strong foes.
One interesting plot twist could be that Percy's water powers somehow interact with Elsa's ice powers in unexpected ways. Maybe when they meet, their powers combine to create a new form of frozen water element that has unique properties. Another could be that the demigods from Percy Jackson's world have to deal with the magical cold of Arendelle, which is a whole new kind of challenge compared to their usual Greek - related threats.
Perhaps a plot twist where the Mist from Percy Jackson's world starts to affect Tokyo Ghoul. The Mist could make humans in Tokyo see ghouls as something completely different, like mythical creatures from their own Japanese folklore. This would not only change how the humans in Tokyo Ghoul react to ghouls, but also how the ghouls themselves perceive their place in the world and their relationship with humans.
One interesting plot twist could be that Percy discovers a way to nullify Kratos' god - given powers. Maybe he finds an ancient artifact during the fight that has the ability to do so. Another could be that Kratos, instead of seeing Percy as an enemy, realizes they have a common goal against a greater evil in the fanfiction world and they end up teaming up.
In some fanfics, a plot twist could be that a demigod turns into a vampire. This completely changes the dynamic as they now have to deal with their new vampiric nature while still having their demigod powers. It's a really unique take on the crossover.
One interesting plot twist could be when Atalanta turns out to be a long - lost relative of one of Percy's friends. This completely changes the dynamic between them and adds a whole new layer of complexity to the story.