Even when a writer says they actively avoid developing a theme in their writing, concepts and morals emerge, even if the idea is as simple as “the good guys always win.”
For the rest of us, we approach our writing with some concept of universal truth or the human condition that we want to examine. Your theme might a single word, such as justice or honesty, or a phrase like the value of art or the need to live authentically. Our themes can guide our writing when we turn them into value statements. A life without artistic expression isn’t worth living. A man cannot reach his full potential unless he lives an authentic life.
Sometimes, themes sneak up on us when we aren’t paying attention. We create characters with similar backgrounds or foibles without realizing it. Or we use protagonists of vastly different personalities to examine the same idea.
For example, you might realize that many of your protagonists lack family or have a problematic relationship with one. Maybe your characters often seek their place in the world, in addition to their unique story goal. Perhaps your heroes wonder about their identity and the kind of person they want to be, despite their circumstances and past mistakes.
Take some time today to look for patterns and similarities in your work. Are the sheriff in your 19th century western and the middle school girl in your fantasy both loners? Are many of your protagonists orphans? Are your heroes often portrayed as the “little guy” fighting a powerful antagonist, with the odds against them? You might also find patterns in opposites.
See if you can make connections between your work. This doesn’t have to be a serious exercise, but working through it might highlight ideas simmering below your conscious thoughts and reveal meaningful themes you might want to examine more intentionally in your writing.