One possible plot could be Percy having to overcome some sort of magical or divine interference. Maybe he has to prove his worth to Gaea in a series of trials. Another aspect could be how the other demigods react to this union. Some might be in shock, while others might try to stop it for the greater good.
The plot might be set in a world where the rules of the original Percy Jackson universe are slightly twisted. Percy marries Gaea not out of love but as a means to an end. Maybe to save his friends or the world from a greater threat. The story could then focus on how he navigates this new relationship while still staying true to his values. He might have to use his wits and powers to outsmart Gaea and her minions who are constantly trying to take advantage of the situation.
The plot might involve Percy gathering ancient artifacts or allies. He could go on a quest to find a weapon that can harm Gaea on a fundamental level. Along the way, he overcomes many challenges and personal demons. When he finally faces Gaea, he combines his strength, the power of his friends, and the magic of the artifacts to completely destroy her, bringing peace to the world of the gods and demigods.
The fanfiction might explore Percy's relationships in a new light. For example, his relationship with Annabeth could be strained as he now has loyalties to Gaea. His friendships with other demigods might also change drastically. Maybe he'd be seen as a threat and have to fight against his former allies. Overall, it would be a complete upheaval of the original Percy Jackson story dynamics.
In this fanfiction, there could be a prophecy about a lemon that will either save or doom the world in the face of Gaea's threat. Percy Jackson is tasked with finding this lemon. Along the way, he meets various characters who either help or hinder his quest. When he finally finds the lemon, he has to make a difficult choice. If he gives the lemon to Gaea, she might spare some of his friends but would gain enough power to cause great destruction. If he destroys the lemon, he risks angering Gaea and starting a full - scale war. So, he has to find a third option that no one has thought of before.
In a 'Percy Jackson Husband of Gaea' fanfiction plot, perhaps there's a prophecy that foretells of Percy being united with Gaea. Percy initially resists, but as events unfold, he realizes that there's more to Gaea than just the evil entity he thought she was. They could start to work together to bring about a new order in the world of the gods and demigods. Along the way, they face opposition from other gods who see their union as a threat. Percy has to balance his loyalty to his friends and his new - found relationship with Gaea, all while trying to understand his role in this strange new world order.
Obviously, Percy and Gaea would be the main characters. But there could also be other characters like Annabeth. She might be heartbroken at first when she hears about Percy's marriage to Gaea. And then there could be some of the other demigods like Jason or Piper who would be involved in trying to understand what's going on and maybe even stop it if they think it's a bad thing.
One possible plot could be Percy discovering his true parentage as Gaea's eldest son and struggling with the implications. He might have to face the wrath of the other demigods who see Gaea as an enemy. For example, he could try to convince his friends like Annabeth that he is still on their side despite his newfound origin.
The plot could involve Percy's journey to discover the true meaning of being the son of Gaea and Pontus. He could be on a quest to find out more about his parents' realms and how they interact with the world of the demigods. Along the way, he may encounter mythical creatures that are related to Gaea and Pontus, and he has to either fight them or make peace with them. There could also be a sub - plot about Percy's relationships with his friends at Camp Half - Blood, as they struggle to accept this new side of him.
One possible plot could be Percy's discovery of his true parentage. He might struggle with the implications of being the son of two powerful primordial deities. For example, he could face a conflict between the forces associated with Ouranos and Gaea. This could lead to him having to make difficult choices about which side to support, if any. And he may also have to deal with the reactions of his friends and the other demigods who might view him differently now.
In the 'percy marries a goddess fanfiction', perhaps it starts with Percy accidentally stumbling into the goddess's domain. She is initially cold towards him but as they spend time together, she realizes his good heart. Percy, on the other hand, is in awe of her beauty and power. Their relationship develops slowly, facing opposition from other gods and goddesses who think it's not proper. But they overcome all the odds and marry. Their marriage could then be a symbol of a new era of cooperation between mortals and immortals in the fanfiction world.
Well, in this fanfiction, perhaps there's some sort of magical interference that makes Percy and Hera fall in love. It could start with Percy accidentally stumbling upon a powerful magic that binds their fates together. And then he has to navigate the complex world of the gods while dealing with his new relationship with Hera. He might face opposition from other gods who don't approve of their union, and he'll have to find a way to win them over.