Well, it could be about Harry discovering his new heritage as the son of Hecate. Maybe he'd learn new magic that's related to Hecate's domain, like more powerful divination or magic over the crossroads. He could also face challenges from those who oppose a half - god in the wizarding world.
In some fanfictions, Harry Potter being the son of Hecate can bring a whole new set of magical abilities and connections. It might mean he has an even deeper understanding of magic that is more ancient and primal compared to the magic he learned at Hogwarts. However, this is purely in the realm of fan - created stories and not part of the official Harry Potter canon.
Well, a plot could involve Percy getting caught in a magical feud between different factions related to Hecate. He might have to use his combat skills along with his newfound magical abilities to resolve the situation. Also, a story where Percy has to protect a sacred place related to Hecate from monsters would be interesting. He could learn about the secrets of Hecate's magic in the process.
Well, Harry Potter is a given. Hecate, as his mother in this fanfiction concept. His friends Hermione and Ron would be key characters as they always are in Harry's story. There could be magical professors at Hogwarts who notice the changes in Harry due to his new heritage. Additionally, there could be some minor characters from Greek mythology, like nymphs or satyrs, that make an appearance. There might also be some descendants of other gods or goddesses who either befriend or oppose Harry based on his relation to Hecate.
The Titans could still be antagonists. Since Percy has a connection to Hecate, they might see him as a threat to their plans of overthrowing the gods. They could try to capture him to use his powers for their own evil purposes.
Well, it could be a really wild and interesting story. Harry being the son of Poseidon and Hecate would mean he has a whole new set of powers. Maybe he could control water like his father Poseidon and also have some powerful magic from Hecate. He might be able to use water in his spells in unique ways, for example, creating water - based shields or using water currents to carry him quickly through the halls of Hogwarts.
Another plot could involve Percy's relationship with other children of Hecate. Maybe there's a group of them that he has to lead in a battle against a common enemy. This would explore his leadership skills as well as his connection to his Hecate - related heritage. He might have to learn some ancient spells from them to defeat the foe.
Perhaps a plot point could be the new magical abilities Harry gains from being the son of Hecate. He might be able to control certain elements of magic in a way that other wizards can't. This could lead to him getting into both trouble and amazing adventures. He could also face opposition from some in the wizarding world who are suspicious of his newfound powers and origin.
One common plot element is that Harry has an innate connection to ancient magic. Since Hecate is an ancient goddess, he might be able to access magic that others can't. Another is that he may face opposition from the traditional wizarding community who are suspicious of his new origin. And often, he'll go on a journey to discover more about his mother Hecate and the powers that come with his heritage.
You could also develop his character by showing his interactions with other gods and goddesses. As the son of Hecate, he might attract the attention of some deities who either want to help or hinder him. His reactions to their offers and threats would shape his character. For example, if a god offers him more power but at a great cost, how does Percy respond? Does he accept the power out of desperation or does he hold true to his values? This would show his growth and development.