Indirect characterization is a literary device that authors use to reveal a character's personality, interests, or motifs by means of their thoughts, words, behaviors, actions and the description of their appearance, without making direct descriptions or statements about the character like “She is smart,” for example.
In the excerpt, readers can tell that the author is using indirect characterization because the author reveals the personality of the narrator (also a character) through the character's own words and thoughts about a situation.