The description you provided from "Raymond's Run" employs indirect characterization. This technique reveals a character's traits through their actions, speech, thoughts, or through descriptions provided by the narrator rather than through explicit statements about the character.
In this case, comparing the individual to a circus performer and likening the curb to a tightrope suggests qualities such as balance, skill, and perhaps a sense of danger or risk. The imagery evokes a sense of performance and struggle, allowing readers to infer more about the character's personality and situation without directly stating it.