There might be a Kamisama Kiss fanfiction where the story is told from the perspective of a minor character. For example, a sidekick spirit could tell their version of the events that unfold in the main plot. This could give a fresh and unique view on the relationships and the magical world of Kamisama Kiss.
A Kamisama Kiss fanfiction could also explore what would happen if Nanami didn't become a land god. It could be a story of her normal human life and how she still manages to cross paths with the supernatural beings she would have otherwise been ruling over. This could show a different side of the characters and their dynamics.