One common theme is the struggle with identity. Since Percy is the son of Erebus and Nyx in these fanfictions, he often has to grapple with being different from the 'canon' Percy. Another theme is power. Given his new parentage, he might have different or enhanced powers, and the fanfictions often explore how he uses or controls them.
The theme of acceptance is also quite prevalent. Percy has to find his place among his friends and in the demigod world when his parentage is changed. Also, there are often themes related to the nature of the Underworld, as Erebus and Nyx are associated with it. Fanfic writers might explore how Percy's connection to them affects his view of and relationship with the Underworld. For example, he could have a deeper understanding of the dark and mysterious aspects of it.
The theme of identity is also quite prevalent. Being the son of such powerful and somewhat mysterious entities, Percy might struggle with his own identity. Is he more like his father, Erebus, associated with darkness and shadow, or his mother, Nyx, the night? Fanfictions often play with this idea, showing his journey to understand who he is and where he fits in the grand scheme of the mythological universe.
One common theme is identity. Since Percy is the son of Erebus, he has to figure out who he really is now. Another theme is acceptance. He has to deal with how others in the Percy Jackson world accept or reject him because of his new heritage. And of course, there's the theme of power. With his new connection to Erebus, he often has new and sometimes dangerous powers that he has to learn to control.
Another plot could involve Percy being drawn into a quest related to the primordial world of his new parents. Maybe there's an ancient threat that only someone with his unique heritage can stop. This would take him to places like the Underworld in a whole new light, as he has a deeper connection to the primordial darkness there.
One common theme is the exploration of the unknown. Erebus is a very mysterious place in Greek mythology, so fanfictions often focus on Percy's exploration of it. Another theme is the struggle against darkness, both literal and metaphorical. Since Erebus is associated with darkness, Percy often has to fight against the dark forces there.
One common theme could be the exploration of darkness. Since Erebus represents the primeval darkness in Greek mythology, in fanfiction with Percy Jackson, it might involve Percy delving into the darker sides of the mythological world he inhabits. For example, he could be facing challenges that are more related to the unknown and shadowy elements.
One common theme is identity. Percy has to figure out who he is now that he's the son of Erebus. Another theme is power. His new heritage often comes with new and different powers that he has to learn to control. For example, in many fanfictions, he might have powers related to the underworld like shadow manipulation.
You can start by looking on fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. These platforms have a wide variety of fanfictions. Just search for 'Percy Jackson Son of Erebus and Nyx' in the search bar, and you'll get a list of relevant stories. You can also check out some Percy Jackson - related forums where fans might share and recommend such fanfictions.
One common theme is the power struggle. Nyx being an ancient and powerful goddess, often there are stories about her power in relation to Percy's abilities. Another theme is the mystery. Nyx is a rather mysterious figure in Greek mythology, and fanfictions like to explore that aspect further.
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 exploration of the power dynamics. Since Erebus and Thanatos are such powerful entities in Greek mythology, the fanfictions often deal with how Percy, as a demigod, can either challenge or be overawed by their power. Another theme is the idea of mortality and immortality. Thanatos being the personification of death and Erebus related to the primordial darkness, it makes for interesting discussions about life, death, and the afterlife in the context of Percy's world.