how does Iago use the 'otherness' of Othello and Cassio to isolate them in Venice and on the island of Cyprus

Despite his standing and military prowess, Othello never feels comfortable in Venice because of his otherness. As a Moor, he is constantly stereotyped as "savage" or "animal", even though he speaks eloquently and displays more gentlemanly qualities than those who judge him. Thus, Othello perceives himself to be a rough outsider, though he is nothing of the sort. Othello's race sets him apart, and makes him very self-conscious; it makes him work hard and look carefully after his reputation, so he is regarded as equal to the white people that surround him. Iago preys on these insecurities and easily turns them into paranoia for Othello. Cassio is a smooth-talking Venetian courtier, the opposite of Othello in many respects, which is why Othello admires him. Othello's admiration of Cassio separates Cassio from others, especially Iago. Cassio is also the only male character that does not lust after Desdemona.