Question

a secondary character in a story that the author uses to highlight the protagonist personality or characteristics is called..?

Answer 1

Antagonist - The antagonist is the character that represents the opposition against which the protagonist must contend. In other words, the antagonist is an obstacle that the protagonist must overcome.
Hope this was helpful!

Answer 2

A secondary character in a story that the author uses to highlight the protagonist personality or characteristics is called character foil.

In a story, a foil is a character who contrasts with another character, generally the protagonist, to highlight qualities of the other character. Sometimes, a subplot can be used as a foil to the main plot.

A foil generally either differs dramatically or is extremely similar but with a fundamental difference setting them apart.