Michael Cassio, the Lone Gentleman

Michael Cassio is a gentleman.  The only known of his kind in Othello.  Iago tries to make Othello believe that Desdemona and Michael Cassio are having an affair, and Othello wants no part of this. Micheal Cassio also holds Iago's dream job, lieutenant.

Michael Cassio's kissing of other's wives was once actually the polite thing to do, unlike now where Cassio would have started a fight.  This is the biggest act of being a gentleman so far in Othello.  Michael Cassio is the gentleman.

Iago decides to stir up trouble and make Othello believe that Michael Cassio and Desdemona are lovers.  Cassio's nature of being a gentleman backfires on him, others see him kiss Desdemona and this adds plenty of fuel to the fire to make Othello believe that the affair is really going on.

The lieutenant of Othello's army is  Michael Cassio, Iago deeply desires this job and he wants to get out of being the flag bearer.  Iago gets very jealous of Michael Cassio's job and fuels his desire to bring down Cassio.