In Othello, Iago is determined to destroy Othello. He is manipulative and deceitful and his skill at playing on the emotions of everyone around him is unmatched. Iago baits many of the characters and persuades them that he is above reproach. Roderigo is easily convinced of Iago's justification in Act I, scene i when he agrees with Iago that he should not "follow" Othello (40). Roderigo is prepared to do whatever Iago wants because he thinks that Iago has the power to help him win over Desdemona. He is more than willing to help Iago convince Brabantio of Othello's "foul charms" (I.ii.73). Iago baits Brabantio by using coarse language and innuendo in describing Desdemona and Othello's relationship. Iago stops at nothing. Even Cassio unwittingly buys into his scheme and behaves out of character, ruining his reputation and presenting Iago with the perfect opportunity to further his cause.
In Act III, scene iii, Iago's plan is so well-formulated that the characters do much of the work for him. The audience watches as Desdemona presents Iago with the perfect opportunity to plant seeds of doubt in Othello's mind. Othello is already disappointed in Cassio's behavior, and it is Iago's subtle suggestion of how Cassio is "acquainted" (100) with Desdemona that makes Othello ask Iago the question "Is he not honest?" Iago knows how important honesty is to Othello and echoes Othello's beliefs when he says "Men should be what they seem" (130). His insistence that Cassio is therefore "an honest man" (133) just serves to drive Othello closer to doing something irrational. The fact that Iago even warns Othello of "the green-eyed monster" (170) increases the intensity and potential for disaster.
This clever baiting makes Othello impatient and anxious. He knows (he thinks he knows) that there is more to the story and by Iago echoing him, of which Othello is aware and which makes him even more determined, Iago guides Othello towards having to convince even himself that Desdemona "had eyes and chose me" (193). The audience can see what Iago is doing and desperately wants Othello to hold on to his integrity but the audience also sees him slipping further under Iago's influence but can do nothing to stop him. This makes this scene very dramatic and significant in terms of the development of the plot. The audience or reader wants to intervene on Othello's behalf but watches helplessly on.