Universality is a theme in theoretical computer science. The concept of a computer is universal because the various models people have come up with - Turing machines, register machines recursive functions, lambda calculus… - can all simulate each other. Similarly, a problem that is NP-complete can be encoded as any other NP-complete problem; we write A <=_P B to mean that any problem in A can be rephrased as a problem in B. When we want to show B is NP-complete, we find an NP-complete problem A and show that it can be reduced to B.
I propose a concept called story-completeness (or life-completeness).
Stories are about one specific thing - going through school, pursuing someone you love, slaying the dragon, etc. - yet can manage to speak very universally about life. So writing a story is like giving a reduction from life to whatever you’re writing about (Life <=_story (subject of story)); somehow in the confines of what your story touches on, you are able to talk about any aspect of life.