One common theme is the power dynamic. Since Nyx is a very powerful figure and Percy has his own set of powers, exploring how they interact in terms of power is often seen. For example, in some fanfictions, Percy has to learn to respect Nyx's greater power while still standing up for himself.
Yes, there are some Percy Jackson and Nyx romance fanfictions out there. You can usually find them on popular fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'Percy Jackson Nyx romance' on those sites, and you'll likely come across a variety of stories with different takes on their relationship.
A simple fanfiction idea could be that Nyx senses Percy's unique power and decides to mentor him secretly. She could teach him ancient and powerful magic that no one else knows.
One possible fanfiction could be about Percy having a mysterious encounter with Nyx in the Underworld. Maybe he stumbles upon her realm while on a quest and has to face her challenges.
One common theme is the idea of an unlikely union. Percy, a demigod, and Nyx, a goddess, are from different strata of the mythological world, so their coming together is always an interesting exploration.
Fanfiction.net is also a good place to look for Percy Nyx fanfiction. There are many talented writers who post their works there. However, you might need to use the search function and type in relevant keywords like 'Percy' and 'Nyx' to narrow down the results and find the stories you're interested in.
One possible fanfiction could be about Percy Jackson accidentally stumbling into Nyx's realm. He's initially terrified but then realizes Nyx has a different side to her. They start to have an unexpected connection, and the 'lemon' aspect could be a budding romantic or at least a very intense friendship that has some flirty undertones. For example, Nyx might show Percy some hidden powers that are only known in her domain, and in return, Percy shares stories of his adventures with the Olympians.
A simple idea for such a fanfiction could be that Percy is exploring a new part of the mythological world and comes across Nyx. Their encounter is filled with a sense of mystery and danger. The lemon aspect might be a moment where they share a glance that holds a lot of unspoken emotions. It could be a starting point for a relationship that defies the norms of the Percy Jackson world, like a hero getting involved with a more primordial being.
The theme of loyalty also pops up frequently. Percy has to decide where his loyalties lie - with his newfound heritage related to Nyx, with his old friends from Camp Half - Blood, or with the gods who now view him with suspicion. Fanfictions explore how he navigates these complex loyalty issues.
One common theme is the power dynamic. Given that Nyx is a very powerful figure in Greek mythology and Percy has his own set of powers, their relationship often explores who has more influence. For example, in some fanfictions, Percy has to learn to navigate Nyx's vast power.