He would likely be very strong in water - based powers. For instance, he could have the ability to create powerful whirlpools or tsunamis with ease. He might also have a natural affinity for sea creatures, being able to communicate with them effortlessly. This would make him a great protector of the underwater world.
Percy might possess a regal and noble air, given his mother is Amphitrite. He could be very diplomatic, having to deal with the various personalities and politics in the underwater kingdom. He may also have a bit of a mysterious side, as the son of a powerful sea goddess, with secrets about the deep sea that others don't know.
In fanfiction, Percy could be extremely loyal to his family in the sea. He would fight tooth and nail to protect his mother Amphitrite and any siblings he might have. His appearance might be a bit otherworldly, with eyes that seem to hold the secrets of the ocean and a physique that is well - adapted for life in the water, like webbed hands or feet perhaps.
One possible plot could be Percy discovering his true parentage as the son of Amphitrite. He might struggle with his identity, as he has always known Poseidon as his father. This could lead to a journey of self - discovery where he has to learn about Amphitrite's powers and how they are now a part of him.
One interesting plot could be Percy's adventures in the underwater realm as the son of Amphitrite. He might discover new sea creatures and magical underwater places. Another could be his interactions with other demigods from a different perspective, since his mother is Amphitrite.
Well, it could be about Percy having to adapt to his new divine family. Maybe he has to learn special water - related powers from Amphitrite that are different from what he already knows. He could also face challenges from other sea deities who are jealous of his new status.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). There are often many talented writers who create stories about Percy being the son of Poseidon and Amphitrite. Another option is FanFiction.net. Just use the search function and type in relevant keywords to find some great reads.
Some of the traditional sea monsters like the Kraken could be antagonists. Since Percy is now in a more prominent position in the sea world as Amphitrite's adopted son, the Kraken might see him as a threat and try to attack him.
Obviously, Percy Jackson himself. Since it's about him being the son of Amphitrite. Also, Amphitrite is likely to be a main character, as she is his mother. Other characters could include his friends from Camp Half - Blood, like Annabeth, who might have to deal with Percy's new identity and the changes it brings.
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.
Well, it could be that in Percy fanfiction, Percy shows courage and a connection to the sea world. Amphitrite, being a sea goddess, would be drawn to these stories. For example, if Percy is shown protecting the sea or having a special bond with sea creatures, it would appeal to her. Also, the fanfictions might depict new and exciting aspects of the sea world that she would enjoy reading about.
Another theme is family. Amphitrite is related to Percy through Poseidon. Fanfictions may explore how this family connection affects their relationship, whether it's a source of conflict or a way to bring them closer. It could involve Percy having to deal with Amphitrite as a sort of step - mother figure in some stories.
A plotline could revolve around Percy discovering his unique powers as the son of Amphitrite. Maybe he has the ability to control not just water, but also the emotions of sea - dwelling beings. This could lead to a story where he has to use this power to calm a raging sea god who is about to destroy coastal cities in a fit of rage. He would have to navigate the complex politics of the underwater realm as well, as there could be factions that either support or oppose his new - found power.