Here on Enotes there is one outline that may help you some; it is Topic #2 on Iago. See the link below, and there is another link to a student paper on Iago's jealousy that you may be interested in reading; also you may want to read the essays from the works cited page. That link is also below. In addition, here are questions which will ignite ideas for you; these are from another site, called Shmoop:
- What language does Shakespeare use to describe jealousy in the play? Do different characters use different metaphors to describe jealousy, or are there common ways of talking about it?
- Do other characters besides Othello demonstrate jealousy? In what ways?
- Is jealousy portrayed as intrinsically unreasonable? Is there a kind of jealousy that is reasonable, or does the play suggest that all jealousy tends to "mock" the person who is jealous?
- Why is sexual jealousy the focus of the play, rather than a different kind of jealousy? What other kinds of jealousy are included in Othello? (If you're thinking of Iago's jealousy of Othello, keep in mind that this, too, could be sexual jealousy.
Here, too, are some points to consider with respect to Iago's intent to arouse Othello's jealousy:
- Consumed with envy of Cassio, who has been chosen by Othello as lieutenant, Iago plans to avenge himself on both Cassio and Othello by making Othello jealous.
- Iago is the "innocent instigator": He begins with a strong statement, but follows with a question which he answers himself, then ends with a strong assertion.
- Iago employs innuendo, planting seeds of doubt, then he appears to be reluctant to criticize, thus blurring reality. For instance, he points out to Othello that Desmonda deceived her own father by marrying Othello, so why would she not be deceitful again. In another instance, when he is with Othello and they see Desmonda and Cassio together, Othello asks, "Was not that Cassio parted from my wife?" and Iago replies slyly,
Cassio, my lord! No, sure, I cannot think it,
That he would steal away so guilty-like,
Seeing you coming. (3.3.38-40)
- Iago is deceitful in his jealousy of Cassio. He has his wife copy the scarf of Desmonda so that he can "plant it" and deceive Othello, thus arousing his jealousy, knowing that "Trifles light as air/Are to the jealous confirmations strong" (3.3.323-324).
- Iago even creates false conversations. For instance, he tell Othello that he overheard Cassio in his sleep saying,
Let us be wary, let us hide our loves." (3.3416-417)
- Iago also creates scenes, saying that he has observed Cassio wiping his beard with Desmonda's handerchief, but first feigning no knowledge of Othello's having given her the article:
I know not that. But such a handkerchief--
I am sure it was your wife's--did I today
See Cassio wipe his beard with. (3.3.437-439)
Interestingly, jealous is ignited in the characters by only circumstantial evidence, an indication of the insecurity in these characters