Othello: Roles of Cassio, Roderigo, and Brabantio, and their functions From Shakespeare's play Othello, this paper will be discussing the roles of Cassio, Roderigo and Brabantio, and their functions. First, Cassio. Cassio is an honourable lieutenant and a soldier, who is very loyal and caring towards his commanding officer, Othello, as shown in one of many places, act two scene one line 45-48 when he is concerned about Othello's well being because he has been lost at sea and says: Thanks, you the valiant of this warlike isle, That so approve the Moor! O, let the heavens Give him the defense against