One possible theme could be cooperation. As mentioned before, their different skills can lead to a great partnership. Another theme might be the contrast between their natures. Hephaestus' more physical and hands - on work compared to Athena's intellectual pursuits.
The theme of admiration could be prominent. Hephaestus might admire Athena's wisdom, and Athena could admire Hephaestus' craftsmanship. It could also be a story about how two very different deities find common ground. Maybe there's a theme of discovery, where they each discover new aspects of themselves or their powers through their interactions with each other.
One common theme is the exploration of their different natures. Hephaestus, being the god of fire and forge, and Athena, the goddess of wisdom. Their relationship in fanfiction often delves into how these two different aspects interact. For example, how Hephaestus' practical skills might complement Athena's intellectual abilities.
It could be a story full of creativity. Hephaestus, the god of blacksmithing, and Athena, the goddess of wisdom. Maybe it could show how Hephaestus creates amazing artifacts with the wisdom and inspiration provided by Athena. Their interactions might involve Hephaestus seeking Athena's advice on his works, and Athena being impressed by Hephaestus' craftsmanship.
Another theme could be the idea of acceptance. Percy, being a demigod, might face some challenges in being accepted by Hephaestus, who is a god. And Hephaestus, with his own insecurities, might also struggle to accept Percy in some fanfics. This creates a lot of emotional depth in the stories.
One common theme is the clash and then the eventual understanding between two very different cultures. Naruto's world of ninjas and Athena's more mythological world. Another could be the power - up theme, where Naruto might gain some abilities related to Athena or vice - versa.
The key event was Hephaestus' unwanted advance towards Athena. As a virgin goddess, Athena didn't tolerate it. This led to the strange birth of Erichthonius.
In Greek mythology, Athena and Hephaestus don't have a typical 'love story' in the romantic sense. Hephaestus once tried to assault Athena. But Athena, being a virgin goddess, resisted him. This event led to Hephaestus spilling his semen on the ground, which gave birth to Erichthonius in a rather strange way.
Fanfiction.net might also have some 'aphrodite x hephaestus fanfic'. You can browse through different categories and use the search function. However, keep in mind that the quality can vary widely. Look for stories with high ratings and positive reviews. Some authors might also have their own blogs or websites where they post their fanfics, so it could be worth doing a general internet search for those as well.
In a 'aphrodite x hephaestus fanfic', one could expect to see a lot of emotional drama. Since Aphrodite was often associated with affairs and Hephaestus was her husband in some myths, the fic could delve into their marital issues. It might show how Hephaestus deals with Aphrodite's unfaithfulness or how Aphrodite feels trapped in a marriage with someone she doesn't fully love. The fic could also explore the idea of redemption and forgiveness in their relationship.
One common theme is mentorship. Since Phoenix has more experience, many fics explore him guiding Athena in her legal career.
One common theme could be the exploration of Hephaestus' character in a new light. Since he is often depicted as a rather complex figure in Greek mythology, in gay fanfic, it might be about his relationships and how his skills as a craftsman play into his love life.