I love this insight from Laura Oliver on the writing life, in a post called “Territory.” She discusses the themes that can permeate our writing, sometimes over a lifetime. (I’ve also heard this phenomenon called one’s “ultimate life concern.”)
Here’s a snippet:
Most writers have a territory they explore for a time—perhaps an entire career. It is the theme, subject, or question that predominates their work. It might be a belief they hold—love triumphs over all, everyone lies—and it might appear as a question, not an assertion. … This kind of revisiting makes possible a remarkable intensity of observation, which in turn can elevate work to a higher plane. What many writers find is that intense contemplation of a single theme gives a freshness and individuality to each story even when the subjects are similar.