Similarly, sometimes there can be multiple social relations between characters within a narrative setting; somebody might be both a friend and a parent, for example. Properly modelling this requires allowing multiple distinct edges between vertices.

And, finally, technically any hypergraph with path equivalence is a category.

When I'm doing narrative analysis on a whiteboard, the diagrams that I draw are category-theoretic, not graph-theoretic, and I'd like to be able to bring that richness into my narrative-mapping tool without having to flatten everything down into annotated graphs.