Hardly. While fanfiction can cover a wide range of themes, abuse is not a typical or popular one, especially when it comes to well - liked characters like Yukio and Rin. The majority of fanfiction writers are interested in creating engaging stories that build on the existing relationships in a positive manner. Depicting abuse would not only be out of character for most interpretations but also not well - received by the general fanfiction - reading audience.
Well, Yukio acquires powers in the manga. These powers play a crucial role in shaping the plot and his character arc. They give him new abilities and challenges to face.
If Yukio was a girl, it could open up new storylines and themes. For example, how society perceives her or how her gender influences her goals and choices could be explored in the fanfic.
A common theme is friendship. Since they are often portrayed as friends, fanfics explore how they strengthen their bond. Another theme could be growth. They might grow together as individuals while being in this relationship.