Percy would develop a more global perspective. Instead of just thinking about Camp Half - Blood or his immediate friends, he'd consider the well - being of all beings in the universe. His sense of justice would expand, and he might become more diplomatic in dealing with different powers. He'd also learn to control his power better as being the king comes with great power that needs to be managed carefully.
Percy's character would develop in many ways. Firstly, he'd gain a deeper understanding of the politics among the gods. This would make him more calculating and strategic. He'd also become more empathetic towards the gods' viewpoints, even if he doesn't always agree. His relationships with his old friends would change too. He might not be able to be as carefree with them as he used to be. Instead, he'd have to consider how his actions as king affect them and the entire demigod community. Moreover, his sense of responsibility would expand far beyond just protecting his friends and family to safeguarding the entire divine and mortal worlds.
In many fanfictions where Percy becomes the God of the Universe, his character often develops a more profound sense of responsibility. He starts to see the bigger picture of the cosmos. For example, he might become more detached from his former mortal relationships as he has to deal with the grandeur of the universe. His power also changes his perspective. He may start to view the various pantheons differently, not just as separate entities but as parts of a greater whole that he now oversees.
His character would become more confident in his artistic abilities. Apollo is the god of many arts, so Percy would likely be exposed to music, poetry, and painting. He might be more flamboyant in his actions and speech, as Apollo has a certain charm. For example, he could start using more flowery language when talking to his friends or enemies.
Percy's character would likely become more in tune with nature. He'd be more reserved perhaps, as he grows up in an all - female group. His sense of honor might be more shaped by Artemis' values, such as protecting the weak and the natural world.
His character could develop in a way that he becomes more powerful. Since Kronos is a very powerful being, Percy might inherit some latent power. But he would have to learn to control it. He would also become more empathetic towards the Titans in a sense, as he realizes that Kronos is his brother. This could lead to him trying to find a middle ground between the Titans and the gods, which would be a major shift in his character from just being a defender of the gods.
Percy would likely become more confident, given the immense power he's gained from absorbing Ouranos. He might also become more solitary, as he tries to understand and control this new power within him.
Percy would likely become more diplomatic. As Hera's husband, he'd have to deal with all kinds of divine politics, so he'd learn to be more tactful in his words and actions.
Percy's character would likely become more versatile. He'd start to incorporate Apollo's traits like confidence and a love for the arts. His power set might expand to include things like healing, which is associated with Apollo. He'd also become more in tune with the sun and light, which could change his overall perspective on things.
Percy might become more confident in his abilities. Knowing he is related to Achilles, a great hero, could give him a boost. He may also become more strategic in combat, learning from Achilles' military tactics.
Percy might become more in tune with nature. Geia is all about the earth, so Percy could start to understand and feel the rhythms of the natural world more. For example, he could sense when an earthquake was coming or know where to find a hidden spring.