Perhaps an OC from a different clan of spirits who comes to the Nura clan seeking refuge. Rikuo takes the OC under his wing, and they grow together. The OC could bring new skills or knowledge to the Nura clan, and a relationship could blossom between the two as they face various challenges together.
You can start by looking on popular fanfiction websites such as Archive of Our Own (AO3). It has a large collection of fanfiction from various fandoms, including Nurarihyon no Mago. Just use the search function and type in 'Nurarihyon no Mago Rikuo x OC' and you should get relevant results.
One common theme is the development of their relationship. It often explores how they grow closer over time, from just being friends or comrades in the yokai world to something more romantic. Another theme could be the challenges they face together, like dealing with other yokai who might oppose their relationship.
Well, first of all, you could start by checking out some anime - related forums. There are often threads dedicated to sharing fanfiction. For example, Reddit has some sub - forums for Nurarihyon no Mago fans. People might post their own Rikuo x Tsurara fanfictions there or recommend good ones they've read. Another option is to follow some fanfiction writers on social media platforms like Twitter. Sometimes they'll announce when they've written a new piece for this pairing.
You could also write a fanfic centered around a tournament among the youkai. Each youkai would have to use their unique abilities to compete. The Nura Clan members could participate, and it would be a great way to showcase different powers and relationships within the world of Nurarihyon no Mago. This could also lead to some interesting rivalries and alliances being formed during the tournament.
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.
A distinct personality for the male OC. He could be brave yet cautious, or maybe he's a bit of a trickster. This personality should be consistent throughout the story.
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.
You can also consider creating relationships for the male OC. He could form friendships or rivalries with the existing characters. For instance, he might become friends with Rikuo and help him in his journey to lead the Nura Clan. This would not only make the story more engaging but also give the OC a purpose within the world of Nurarihyon no Mago.
In some fanfictions, there's the idea of cross - world reincarnation. A character from Naruto could be reincarnated in the world of Nurarihyon no Mago with some of their previous memories intact. This creates really interesting storylines as they try to make sense of their new existence while still having ties to their old world. Also, the concept of combined teams, like a team consisting of both ninja and yokai, is quite unique. They have to learn to work together despite their very different natures.
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.