Another plot could be that there is a rift between the worlds of angels and demigods that is causing chaos. Archangel Gabriel is tasked with closing the rift, but he needs Percy's help as Percy has a unique connection to the elements. Along the way, they face challenges from both sides who don't want the rift to be closed, and they have to fight against all odds to restore order.
Another idea is that there is some sort of prophecy that links Percy and the Archangel Michael. This prophecy could force them to interact, and they initially might be at odds with each other due to their different natures. Percy is a half - blood, used to the chaos and grey areas of the demigod world, while Michael is a pure celestial being. But as the story unfolds, they learn to work together.
Well, he could be a messenger in the fanfiction. Just as he is often depicted as a messenger in religious texts, he could bring important news from the celestial realm to the demigod world. Maybe he warns Percy about a new threat that is coming from a place that the demigods have no knowledge of. And his presence could stir up a lot of questions among the characters about different mythologies and how they all connect.
One possible plot could be that Bella Swan is suddenly transformed into Archangel Gabriel. She has to hide this new identity from her friends and family in Forks at first. As she discovers her new powers, she starts to sense a dark force approaching Forks. Using her angelic powers, she battles this force while also trying to maintain her normal life, which includes her relationship with Edward. Eventually, she reveals her true self to her loved ones and they all work together to save the town.
Well, perhaps the archangel and Percy would have a power struggle at first. Percy is used to being in charge in his own adventures, and the archangel has its own set of divine powers and authority. They'd need to learn to work together, like when they encounter a group of mythical creatures that are causing havoc in both their domains.
In a more complex plot, Percy could be forced into a boxing match by a powerful enemy who wants to humiliate him. But Percy turns it into an opportunity to unite the demigods. He uses the boxing ring as a platform to give inspiring speeches between rounds. And as the matches progress, he gradually gains the respect of both his allies and former foes through his tenacity and skill in the ring.
One possible plot could be that the entire Greek pantheon is thrown into chaos. Percy might be seen as a huge threat, and other gods and goddesses would either try to hunt him down or form alliances with him out of fear or a desire for power. Demigods would be forced to take sides, leading to massive battles among them.
In fanfiction, Percy might discover a hidden connection between his powers and the archangel's. Maybe there's a prophecy that links them, and they have to figure out how to fulfill it together. The archangel could teach Percy some new skills or perspectives that are different from what he's learned in the demigod world.
In some Percy Jackson fanfiction, archangels are often portrayed as extremely powerful beings. They might be depicted as having abilities far beyond those of the regular demigods. For example, they could have the power to manipulate celestial energy in ways that are unique to them. Their appearance is usually described in a very majestic way, with glowing auras and large, magnificent wings.
One common theme is the clash of different mythologies. Since Percy Jackson is based on Greek mythology and archangels come from religious or angelic lore, seeing how these two different systems interact is often explored.
One possible plot could be Percy waking up one day and finding himself back at the start of his journey at Camp Half - Blood, but with all his memories intact. He could then use this knowledge to avoid the mistakes he made before, like getting in unnecessary fights with some of the other campers. He might also try to befriend some characters earlier who he didn't get to know well in the original story.