Growth is also a prevalent theme. Both Hinata and Yachi grow as individuals in the series, and in fanfiction, their relationship is often part of that growth journey. For example, they might help each other overcome insecurities and become better versions of themselves.
One common theme is friendship. Their initial friendship forms the basis of many fanfics. For example, in some fanfics, they start as just friends but then develop a deeper bond as they support each other through tough times.
There's also 'Hinata and Yachi's New Beginnings'. This fanfic focuses on their friendship evolving into something more. It has some really cute moments where they support each other during tough volleyball matches.
One common theme is the 'unrequited love' at the start. Hinata has a crush on Kiyoko, so many fanfictions play with that dynamic, showing his attempts to get closer to her. Another theme is 'growth', like how Hinata's growth as a volleyball player might make him more appealing to Kiyoko or how they both grow as people through their interactions.
A common theme is their growth as volleyball players. In many fanfictions, they start off with their initial rivalry and then gradually learn to work together better. For example, they might overcome their differences in playing styles and develop new strategies together.
One common theme is friendship development. Since Hinata and Kenma are from different teams, their relationship evolving from acquaintances to friends (or more) is often explored. Another theme could be how they support each other's growth in volleyball.
A common theme is friendship. Their relationship on the volleyball court is a strong base for a great friendship in these fanfics. Another is growth. They both grow as players and as people because of their interactions. And teamwork is also often highlighted, as they are a crucial duo in the team.
One great 'Haikyuu Yachi Fanfiction' is 'Yachi's Growth'. It shows her journey of becoming more confident in the Karasuno team. Another is 'Yachi and the Volleyball World', which dives into how she experiences the intense volleyball matches from her unique perspective. And 'Yachi's Hidden Talents' is also a good read, exploring some skills of Yachi that we don't get to see much in the original anime.
One common theme is friendship development. Since they are both characters in the same story, their friendship is often explored in depth, like how they support each other through tough times. Another theme could be the discovery of new feelings. For example, they might start to realize they have more than just friendly feelings for each other.
One common theme is the 'opposites attract' scenario. Kuroo is often portrayed as confident and a bit of a tease, while Yachi is more shy and reserved. Their interactions based on these personality differences are fun to read.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of 'Haikyuu' fanfictions, including many focused on Yachi. Another option is FanFiction.net, which also has a decent number of 'Haikyuu Yachi' stories.