Not even for a moment does Iago allow the audience even the slightest opportunity to believe that there may be some good or selfless deed in his actions. “When devils will the blackest sins put on / They do suggest at first with heavenly shows, / As I do now” (II.iii.325-327). He constantly restates that his motives are sinister and that he is plotting against everyone, while making himself look like the honest and loyal friend.
Iago pretends to be Othello’s loyal friend, in order to gain his trust and dupe him into believing that Cassio and Desdemona are having an affair. “I am glad of this, for now I shall have reason / To show the love and duty that I bear you / With franker spirit” (III.iii.197-199). Iago seizes the opportunity to elevate himself in Othello’s eyes, and brings up the possibility of Othello’s wife having an affair. “Look to your wife, observe her well with Cassio / Wear your eyes thus, not jealous nor secure” (III.iii.201-202). Iago is cunning, in that he doesn’t tell Othello that Cassio and Desdemona are having affair, but he implies that they might be, just enough to cause Othello to distrust Desdemona and becomes suspicious of her future intentions.
Othello’s hate for Cassio becomes uncontrollable, as he orders Iago to kill Cassio. Iago complies, telling him that he will kill Cassio, whom he refers to as his friend, in an attempt to strengthen Othello’s image of him as a loyal friend who would kill another of his friends for Othello’s sake. “My friend is dead. / ‘Tis done at your request”(III.iii.477-478). Iago wants Cassio dead so that he can never be reinstated as lieutenant and for possibly having slept with his wife. Although Iago acts as though he is doing it to help his friend get revenge on the man having an affair with his friend’s wife, Iago is truly only interested in his own reasoning for wanting Cassio dead. Iago’s plan works out as he planned, as Othello eventually gives him the position of lieutenant. “Now art thou my lieutenant” (III.iii.481). Othello believes that he is rewarding an honest friend, when in reality Iago has duped Othello into getting the military position he wanted.