Michael Cassio is an attractive and good looking Florentine, referred to as a “proper man” (I.3.435) by Iago in the first act of the play. Despite his young age and the fact that he has no real field experience, Cassio seems to be a responsible, brave, and well-disciplined soldier enough to be handpicked by Othello as a lieutenant. He also appears to have a good sense of virtue as he laments the loss of his reputation after he stabs Roderigo and loses his lieutenancy when Iago gets him drunk: “Reputation, reputation, reputation! Oh, I have lost my reputation! I have lost the immortal part of myself, and what remains is bestial“ (2.3.280-283). Cassio is also a loyal soldier who respects and praises his general Othello as “so good a commander” (2.3.297). In addition, the loyalty and trust appear to be reciprocal since Othello entrusts his love letters between Desdemona and himself during their brief courtship to Cassio. In fact, his loyalty, ability, and responsibility are so well-known that the senators and the Duke in Venice decide to make Cassio a new governor in place of Othello Scene 4 Act 1 .
However, while he is generally a good soldier, he has his weaknesses. First, with his “handsome, young” face, and “all those requisites…that folly and green minds look after” (2.1.267-269), he has issues regarding women despite the fact that he is “almost damned in a fair wife”(1.1.22) back home. Despite the fact that he is in a marriage, he finds pleasure in other women including Bianca, a prostitute. Indeed, he is so intimate with Bianca that she is heartbroken to find out that he does not plan on marrying her in the end. Secondly, Cassio has a problem with alcohol in that he has low tolerance for alcohol when he refuses the drink that Iago offers to Cassio because he has a “I very poor and unhappy brains for drinking” (2.3.34-35). He does not drink more than a glass of wine mixed with water as a rule which is why Othello trusts Cassio to take care of the guests ; however, when he does at Iago’s trickery, he loses his ability to think properly as seen when he gets drunk by Iago’s manipulation and attacks Roderigo and Montana.
Cassio is an important character in Othello because he is a key part in Iago’s plan to destroy the lives of Desdemona and Othello. When Cassio becomes Othello’s lieutenant instead of Iago even when “the three great ones of the city, in personal suit to make [Iago] his [Othello’s] lieutenant”(1.1.9-10), believing that he has been cheated, Iago begins to hate Cassio. An evil genius beyond comparison, Iago uses Cassio’s positive qualities such as his handsome face and trusting personality as well as his bad characteristics such as his alcohol and women problems to go through with his plan.