Some of the most powerful details in fiction are the ones we don’t expect. We might call this ironic detail, or perhaps we should just stick with ‘surprise’. Good stories are all about surprise.
Expected detail: The smell of urine on a person is disgusting.
A slight but persistent smell of urine […] would have disgusted me on a woman but […] seemed in his case not just forgivable but somehow an expression of ancient privilege. When I went into the bathroom after he had been there, it was like the lair of some mangy, still powerful beast.Alice Munro, “Cortes Island“
Expected reaction: When you and your family are involved in a car accident, you are pleased to find everyone alive.
“But nobody’s killed,” June Star said with disappointmentFlannery O’Connor, “A Good Man Is Hard To Find“
Expected detail: When a character sets about murdering another character right in front of you, you’d expect their voice to change from ‘thin and pleasant’ to ‘growly and horrible’ or something like that.
Unexpected: When the character doing the murdering doesn’t change their voice. Instead, against expectation, their voice only becomes more thin and pleasant.
I’m talking about Charlotte in Charlotte’s Web, showing Wilbur for the first time how she kills a fly.