You see this everywhere in art – an element is repeated, with some variation each iteration. In songs it’s verses and choruses, in writing it’s usually action or behavior manifested by a character, in comedy it’s the callback.
What makes it so satisfying is this: it sets up an expectation for the viewer/reader/listener that a pattern will repeat – and when it does, their anticipation is rewarded. But it comes with an element of surprise that makes the whole thing irresistible – some new element is added to the pattern.
It’s as if we want to be comforted by anticipating and experiencing repitition, yet we also crave surprise.
Combine them and enjoy the dopamine rush!