His relationships with other demigods would be very complex. For example, the children of Poseidon might see him as an oddity at first. They are used to their own set of powers and Percy having Athena's influence could make them a bit wary. On the other hand, the children of Athena might be skeptical of his loyalty as he also has Poseidon as a father. However, some demigods might be in awe of his unique heritage and look up to him, hoping to learn from his dual nature.
Percy's relationships would likely be a mix of envy and admiration. Demigods from other cabins might envy his connection to two major deities. This could lead to some tension, especially during competitions or when vying for recognition at Camp Half - Blood. But at the same time, his unique abilities from both Poseidon and Athena could make him a valuable ally. He could use his wisdom from Athena to strategize and his powers from Poseidon to execute plans in battles, which would earn him respect from those who understand his value.
The plot might involve Percy trying to bring peace between Poseidon and Athena. There could be some ancient feud between them that Percy is determined to end. He could start by finding common ground between the two deities in their respective domains, like the sea and wisdom. Along the way, he would face many obstacles, including other gods and goddesses who don't want the peace to happen.
His character would likely be a blend of Athena's wisdom and Poseidon's boldness. He'd be more calculating in his actions, thinking several steps ahead like Athena, but also not afraid to take risks when necessary, similar to Poseidon. He might have a natural inclination towards both strategy and brute force, which could make him a very unpredictable and powerful character.
A great plot could be Percy getting caught in a power struggle between Athena and Poseidon's followers. Since he is the son of both, he is a symbol of unity or a threat, depending on how different groups view him. He could be forced to prove his loyalty to both sides while also trying to maintain peace among them. This could involve battles, political intrigue, and lots of character development as he tries to figure out where he truly belongs in this complex world of gods and their followers.
Another plot could involve Percy discovering a hidden connection between Poseidon and Athena that was long forgotten. This could lead to a situation where he has to convince the other demigods that this connection is important for the future of the camp. Maybe there are ancient prophecies that only he can understand due to his unique parentage.
He would probably be a bit of an outcast at first. Since his parentage is so different, other demigods might be wary of him. But once they see his skills and powers, they would start to respect him. He might teach them some unique combat techniques he learned from his Titan mother Rhea, like different ways of using his powers in battle.
Well, Percy's power over water from Poseidon and the wisdom and strategic thinking from Athena could lead to some amazing combinations. For instance, he could use water to create illusions, like mirages in a desert, but with a strategic twist. He could make the illusions in a way that confounds enemies and leads them into traps that he has planned out using Athena - like intelligence.
Percy's powers would be more complex. He could have the ability to communicate with sea deities in a different way. Maybe he could use Hera's diplomatic skills to make deals with them or resolve disputes. His control over water could also be extended to other substances that have a connection to water, like steam or ice, in a more efficient way than before. And his powers of persuasion, which could be influenced by Hera, might be used to calm angry sea storms or make sea monsters cooperate with him, which is an interesting combination of his Poseidon - given powers and Hera - influenced skills.
One interesting fanfic could be where Percy has to deal with the complex politics of having two powerful parents. He might struggle to find his place among the demigods who have more traditional parentage. For example, some might be jealous of his unique heritage, while others might fear his potential power.
One common theme is family. Since Percy is the son of Poseidon and Amphitrite is Poseidon's wife, it often explores how Percy fits into this new family structure. Another theme is power. Percy already has his own powers from Poseidon, and Amphitrite being a goddess also has great power, so how their powers interact is often explored.
In a fanfiction where Percy is the son of Hades and Poseidon, his powers would be truly extraordinary. He could have the ability to create portals in water that lead to the Underworld. This would give him an advantage in both battle and travel. His hydrokinesis could be tainted with the essence of death, so when he attacks with water, it could cause a draining effect on his opponents, sapping their life force. Additionally, he might be able to sense the presence of the dead in any water source, which could be used for both reconnaissance and protection.