Every writer is a fantasist. Whether they’re writing a kitchen-sink domestic drama, romance, YA series about talking dragons, or a mystery novel about a blind accountant who solves crimes, the challenge is the same each time: Make readers believe the world you are creating and the people who inhabit it.

J.R.R. Tolkien explained the importance of this in his essay “On Fairy-Stories“:

The story-maker proves a successful ‘sub-creator’. He makes a Secondary World which your mind can enter. Inside it, what he relates is ‘true’: it accords with the laws of that world. You therefore believe it, while you are, as it were, inside. The moment disbelief arises, the spell is broken; the magic, or rather art, has failed…

Leave nothing to chance. Visualize every aspect of your fictional world. Keep the illusion going. Make readers believe.