The purpose of this paper is to investigate how idioms help the building of opposing characters in a literary work and also what similarities and differences there are in the usage of idioms between the characters. The material, i.e. the idioms, in this study was manually collected from Othello written by William Shakespeare. The material was analyzed and categorized according to a list of idiomatic properties. The material was also analyzed according to the tone of the idioms. The results showed that there was not any prominent difference in usage of idioms between the two characters; neither in general nor in the tone of the idiom. The results suggested, however, that the idioms were used in a negative sense, regardless of character.