One possible plot twist could be that Percy has to hide his true parentage from his friends at Camp Half - Blood. Since Lycaon was a werewolf - like figure and Lupa is associated with wolves in Roman mythology, Percy might have some wolf - like abilities that he doesn't understand at first. For example, he could have enhanced senses like better smell and hearing, which could make him seem different from other demigods. Another plot twist could be that there are other characters who are secretly aware of his true parentage and are either trying to protect him or use him for their own purposes.
In this fanfiction, there might be a lot of focus on Percy's relationship with the other wolves in Lupa's pack. He could learn their ways of survival, their hierarchy, and how to be a part of their community. This would be a great way to explore his adaptability and growth.
For his relationship with the Roman demigods, it could be more complex. Since his parents are related to Roman mythology, the Roman demigods might expect him to side with them more. But Percy has his own values and friendships in the Greek side. This could lead to some tension. His relationship with Chiron would also change. Chiron would need to figure out how to train Percy with his new - found abilities. He might have to seek advice from other sources, like some Roman centaurs perhaps.
Lupa herself would be a major character. She's the one who has a special connection to Percy in this story. She could be guiding him, testing him, or having her own motives that are intertwined with Percy's journey.
The setting of the story might shift a bit. Instead of always being at Camp Half - Blood or on quests related to the Greek gods, Percy could be in the territory of the wolves. There could be new threats and challenges there, like rival wolf packs or ancient enemies of Lupa. And all these elements would make for an exciting and different take on the Percy Jackson universe.
To develop his character further, he could start to have visions or dreams related to Lycaon's past. These could be a source of both knowledge and inner turmoil. He could learn about the mistakes Lycaon made and be determined not to repeat them. At the same time, he might discover some long - lost powers or abilities that Lycaon had, and struggle to master them in a way that is true to his own character.
A prevalent theme is isolation. In many fanfictions, Percy feels alone because of his strange heritage. He doesn't quite fit in with the normal demigods. Also, the theme of destiny often comes up. He has a special destiny due to his parents that he is constantly striving to fulfill.
I've read a fanfiction where Percy is the son of Lupa and Chaos and it focuses on his relationships. 'Percy's Bonds' is the name. It shows how his different heritage affects his friendships and romances, and how he has to come to terms with who he really is in the context of his relationships.
One common theme is identity. Since Percy has two very different divine parents, he often struggles to figure out who he really is in fanfictions. Another theme is power. With the combined powers of Lupa and Poseidon, his power levels and how he uses them are often explored. Also, acceptance by his peers is a big theme as they may view his dual heritage as strange or overpowering.
One interesting plot could be Percy having to prove himself to Lupa's pack in a series of dangerous trials. Maybe he has to hunt a mythical beast that has been terrorizing the pack's territory.