The fact that Iago has all the characteristics of human villainy does not mean that he is not evil incarnate as well. His evil may be inexplicable to Othello, but his motives can be identified. Chiefly, they can be traced to Iago's contempt for others in general and for Othello in particular. Iago's manipulation of sex and race stereotypes unleashes the violence that never far beneath the fear that is itself beneath skewed perceptions. The issue of racial hatred, especially but not entirely on Iago's part, provides an extra element of tension in the action.
These issues surface in the first scene of the play, in which Iago, scorned by Othello in promotion, urges Roderigo to break the news of Desdemona's elopement with Othello to her father Brabantio and so ruin Othello's reputation. Roderigo simply cannot fathom that a Moor could be a successful seducer. It is his characterization of Othello as "the thick-lips" (I.i.66) that is the most revealing. Iago, who resents not being promoted, exploits that sense of betrayal, not just of Roderigo's infatuation with Desdemona but of Roderigo's sense that Desdemona has betrayed her own kind. In this regard, Iago uses coarse language to describe the elopement and the sexuality between Othello and Desdemona as forbidden (and offensive) fruit. He wants Roderigo to explain the details of the elopement, and he incites Roderigo to striking just the right tone by couching his own words in the terms of racial hatred. "Even now, now, very now," Iago tells Brabantio, "an old black ram / Is tupping your white ewe" (I.i.88-89).
If the objection were merely that Othello is a gentleman of a certain age, the reference to black and white would not come into the equation. But Iago is deliberately inflaming the anger of suitor and father, with a view toward destroying Brabantio's hitherto good opinion of Othello. As the scene builds, so does Iago's coarseness. He conjures the image of Brabantio's "daughter ...