Yes, there are some. You can start by looking on fanfiction platforms like Archive of Our Own. There might be various stories exploring their relationship in a married state, with different plotlines and writing styles.
One common theme is love and friendship. Their relationship is often explored in different ways, from a budding romance to a deep platonic bond. Another theme is adventure. They are sometimes put into exciting situations where they have to rely on each other. For instance, they might be on a quest to save their world or something similar.
Another theme could be adventure. Writers might put them in different fictional scenarios, like a magical quest or a dangerous mission, and show how their relationship is affected by these adventures. It gives an opportunity to show their personalities and how they interact in different situations. For example, they might have to rely on each other's strengths to survive.
It could also change how they are perceived by others. Their friends or family (in the context of the fanfiction) might view them differently. Rikuo might be seen as more grown - up or committed, while Tsurara could be seen as more of a partner to Rikuo rather than just a friend. This change in perception could lead to new storylines and interactions within the fanfiction.
I'm sorry I don't have specific 'rikuo and tsurara love fanfic' to recommend directly. You can try searching on fanfic websites like Archive of Our Own or FanFiction.net. Just type in their names in the search bar and see what comes up.
One interesting story could be where Tsurara and Rikuo go on an adventure together through the spirit world. They encounter various challenges and their relationship deepens as they rely on each other to overcome obstacles.
Archive of Our Own is a great place to start. It has a large collection of fanfictions, and you can use the search function to look for stories specifically about rikuo and tsurara being married.
The popularity might stem from the fact that Rikuo and Tsurara have complex characters. In fanfics, authors can delve deeper into their emotions and interactions. Fans love to see how their relationship could develop in various situations, whether it's a more romantic or angsty take on their relationship. Also, for fans who are really invested in the world these characters are from, these love fanfics add another layer of depth to their overall experience of the fictional universe.
Some smaller, niche fanfiction communities dedicated to the same genre or series might also have some excellent tsurara x rikuo fanfiction. You can try to find these communities through social media groups or forums related to the series. Members often share their own works or recommend good stories from others.
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.