One common theme is the bond between them. Since Hyourinmaru is Toshiro's zanpakuto spirit, fanfictions often explore the deep connection and how it affects Toshiro's growth as a shinigami.
Some fanfics explore the idea of sacrifice. Given their connection, there could be situations where one has to sacrifice for the other. For example, Toshiro might be willing to risk his own safety to protect Hyourinmaru, or vice versa. And of course, there are fanfics that blend multiple themes together, creating complex and engaging stories about their relationship.
It offers a chance to see their relationship develop in ways that the original story might not have shown. Maybe in a more romantic or platonic but intense way. Writers can play with their personalities and create interesting storylines based on their mutual understanding and power dynamics.
Social media platforms can also be useful. For example, on Twitter or Tumblr, there are many Bleach fans who create and promote their fanfictions. You can search for relevant hashtags like #Toshiro #Hyourinmaru #Fanfiction. However, the content might be a bit scattered, so it might take some time to find exactly what you're looking for.
Friendship is a very common theme. Hyourinmaru and Hitsugaya have a special bond as a zanpakuto and its wielder. Fanfictions often explore how this bond deepens over time, through shared experiences and challenges. For instance, they might face a difficult enemy together and their friendship becomes stronger as a result.
One common theme is the exploration of their different personalities. Gin is often seen as more sly and unpredictable, while Toshiro is more serious and composed. Fanfictions may play with how these personalities clash or complement each other. Another theme could be loyalty, either in a friendship sense or as comrades in some sort of battle or struggle.
A common theme is friendship. Despite their differences, they often form a strong bond of friendship in fanfics. For example, in many stories, they learn to rely on each other in battles.
In toshiro x reader fanfiction, the theme of redemption can be seen at times. Maybe Toshiro has made some mistakes in the past, and the reader helps him to find redemption. Love and friendship are also prevalent themes. The relationship between the two can start as a friendship and gradually turn into love. There are also themes related to the power dynamics. Given Toshiro's position in his world, the fanfiction may explore how that affects his relationship with the reader. For example, if he has certain responsibilities, how does he balance them with his relationship with the reader? And how does the reader fit into his world with all its rules and hierarchies?
Growth is another theme. The fanfictions usually show how they both grow as individuals and as a couple. For example, Toshiro might become more open - hearted while Momo becomes more confident in her abilities. This mutual growth strengthens their bond. It's often explored through different scenarios like battles or personal dilemmas that they have to overcome.
Friendship is a very common theme. Their initial friendship forms the basis for most stories. For example, they might start as comrades in the Soul Society and then develop a deeper bond.
You can try fanfiction websites like Archive of Our Own (AO3). There are a large number of fanfictions about various pairings, including Hyourinmaru x Toshiro. Just use the search function on the site and you'll likely find many interesting stories.