You can start by looking on fanfic websites like Archive of Our Own. There are often many well - written Crona x Blair fanfics there. Just search for 'Soul Eater Crona x Blair' in the search bar.
In a Crona x Blair fanfic, the story might center around the power dynamics. Blair, being a powerful cat - witch, could play a role in helping Crona control their own power. For example, she might teach Crona some magic techniques that are different from what they've learned at the DWMA. This could lead to a deeper connection between them as they train together.
In many Soul Eater fanfictions involving Blair and an OC (Original Character), the relationship can be quite diverse. It could be a friendship where the OC helps Blair in her various adventures in the Soul Eater world. Maybe the OC has some special abilities that complement Blair's magic. For example, if the OC is good at tracking souls, they could assist Blair in finding more powerful souls to consume.
One common plotline is the OC being a new student at the DWMA (Death Weapon Meister Academy). Blair then takes an interest in this new and unique character. They might start off as strangers, but as the story progresses, they form a bond. For instance, the OC could be targeted by an evil force, and Blair decides to protect them.
A popular theme is the power dynamic between them. Blair has her own unique magical abilities as a witch, and Kid has his skills as a meister. How they combine their powers or help each other improve can be a theme. Additionally, the theme of acceptance is there. Kid has to accept Blair's more unruly ways, and Blair has to accept Kid's strictness. This acceptance can be a journey in the fanfiction, showing how they overcome their initial differences to form a deeper connection.
One great Crona x Soul fanfiction is 'The Bond Beyond'. It delves into how Crona and Soul's relationship develops in a more in - depth way than in the original series. It shows them learning about each other's pasts and how they grow together. Another one could be 'A Different Kind of Friendship'. This fanfiction focuses on how they start as friends but there are hints of deeper feelings emerging as they face various challenges in the world of Soul Eater.
You can start by looking on fanfiction websites like FanFiction.net or Archive of Our Own (AO3). These platforms have a large collection of Soul Eater fanfictions. Just use the search function and type in 'Death the Kid x Blair' to get relevant results. AO3 in particular has a great tagging system, so you can filter by things like rating, length, and genre to find the fanfictions that suit your taste.