One common theme is self - discovery. Since the OC is a son of Hephaestus, they often have to figure out their unique powers and how to use them. Another theme is acceptance, both within the Hephaestus cabin and among the other demigods at Camp Half - Blood.
His character would develop in multiple ways. Firstly, Percy would gain a new sense of discipline. Hephaestus' work demands it. He'd have to follow strict procedures when forging. This would contrast with his more impulsive nature. He'd also develop a new kind of confidence. Knowing he can create things gives him a different kind of power. And he'd probably become more of a team player within the Hephaestus cabin. He'd learn to collaborate with the other kids, sharing ideas and skills. He'd start to understand that his success isn't just about his own abilities but also about how well he can work with others in this new area of expertise. Overall, he'd transform from a mostly solo fighter to someone who can contribute in a group setting in a whole new way.
One great 'Percy Jackson OC son of Hephaestus fanfiction' is 'The Forged Hero'. It follows the story of an OC named Leo Jr., the son of Hephaestus. He has to face challenges in the Camp Half - Blood and prove himself worthy. Another interesting one is 'Hephaestus' Hidden Son'. It shows the OC's journey in discovering his powers and his place among the demigods.
One idea could be Percy having to learn the unique skills of Hephaestus' cabin, like forging magical weapons. He might struggle at first because he's used to his own powers. Another could be him having to deal with the other Hephaestus kids who are initially jealous of his fame as Percy Jackson but then come to accept him. And he could go on a quest where his new skills as an adopted son of Hephaestus are crucial in defeating a powerful monster.
The theme of family also stands out. His relationship with Hephaestus and how it affects his relationships with other demigods, his mother, and the rest of the camp. In some fanfictions, Hephaestus might be a more present and guiding figure in Percy's life, while in others, their relationship might be more strained, but it always has an impact on Percy's family - like connections within the demigod world.
I think Tyson, Percy's cyclops half - brother, would be a good character. His strength and loyalty would be assets in any situation. Also, Nico di Angelo could be in the fanfic. His control over the dead could provide an interesting dynamic, especially if they are exploring some dark or ancient places related to Hephaestus' past works. And of course, Clarisse La Rue. Her combat skills and fierce personality would add some drama and action to the story.
One common theme is Hephaestus' role in helping Percy with his quests. Since Hephaestus is the god of blacksmiths and craftsmen, he might provide Percy with a special weapon or tool. Another theme is the exploration of Hephaestus' relationship with his children in the context of Percy's interactions with them. For example, how Percy might help a Hephaestus - descended character come to terms with their heritage.
Well, one possible plot could be that Percy discovers his new relation to Hephaestus later in his adventures. He might then start to have an affinity for creating and fixing magical items, which could be a new skill for him in battles against monsters. He could also meet other descendants of Hephaestus who teach him more about his heritage.
One great 'Percy son of Hephaestus' fanfiction is 'The Forged Hero' which delves into Percy's journey as Hephaestus' son. It shows how he uses his newfound skills and heritage in battles and problem - solving.
Percy could be accidentally caught in the middle of their relationship drama. For example, Aphrodite might use Percy as a way to make Hephaestus jealous. Or Hephaestus could mistake Percy's innocent interactions with Aphrodite as something more, and Percy has to prove his innocence while also trying not to get too involved in their godly relationship issues.