One common theme is identity. Since the OC is original, a lot of fanfiction explores how they figure out who they are in the context of the Nurarihyon world, whether they're part human, part yokai, or something else entirely.
Friendship and alliances are a big theme as well. Since it's a crossover, fanfics usually show how characters from Naruto and Nurarihyon can form friendships or alliances despite their initial differences. They might work together to face a common enemy, like a powerful dark force that threatens both their worlds.
A common theme is the exploration of their relationship, whether it's a budding friendship or something more. Another theme is the clash of their different worlds and how they overcome the differences.
I'm not entirely sure as I haven't read that specific fanfiction. But generally, it might be about Naruto having some sort of connection to Nurarihyon, perhaps in an alternate universe where Naruto is considered Nurarihyon's son. It could involve Naruto having new powers or a different backstory related to Nurarihyon's world.
The 'nurarihyon no mago light novel' is mainly about a young boy named Rikuo Nura. He is a part - human, part - yokai (demon - like being) and is set to inherit the position of Nurarihyon, the supreme commander of the yokai. The story follows his journey as he tries to balance his human life at school and his yokai responsibilities, dealing with various yokai clans and their politics, and also facing threats from both the yokai and human worlds.
One great 'Naruto and Nurarihyon no Mago' fanfiction is 'The Convergence'. It has an interesting plot where the worlds of Naruto and Nurarihyon no Mago collide in a unique way. The characters are well - written and their interactions feel very natural. Another one is 'Allied Spirits' which focuses on how the different powers from both universes are combined. It's really exciting to see how the author weaves the two stories together.
The complex relationship between them. Nurarihyon is an experienced yokai and Rikuo is the young heir. Their generational gap and different outlooks make for great storytelling.
There are quite a few. You could check out fanfic platforms like Archive of Our Own. Some fanfics there might be centered around Nurarihyon and Rikuo's adventures, or their family dynamics within the yokai society. It really depends on what aspect of their relationship you're interested in.
The cultural clash is also very unique. The shinobi culture in Naruto is all about loyalty to the village, hard training, and honor. The Nurarihyon world has its own culture of yokai hierarchy and trickery. In fanfiction, when characters from both worlds meet, there are often misunderstandings and comical situations due to this cultural difference. For instance, a yokai might not understand the concept of a ninja mission and accidentally disrupt it. And also, the character designs from Nurarihyon, with their unique and often spooky appearances, add a new aesthetic to the Naruto universe in fanfictions.