What does Iago do to Cassio?

In respect to this, how does Iago manipulate Cassio?

Iago manipulates Cassio by convincing Cassio to drink, knowing that Cassio vulnerability is getting mouthy when he is drunk. Iago knows that this can cause Cassio to get fired. It was clear that Iago successfully used Cassio's weakness to get what he wants by getting Cassio fired because of his drunken anger.

Also Know, how does Iago discredit Cassio? Iago believes that Cassio and Des are in love, however, he thinks Othello will try to be a great husband. He thinks Othello slept with Emilia. He thinks he loves Des, but simply as revenge against Othello. He plans to discredit Cassio by getting him drunk.

In this regard, how does Iago convince Cassio to drink?

He tells Cassio that he suspects Desdemona to be a temptress, but Cassio maintains that she is modest. Then, despite Cassio's protestations, Iago persuades Cassio to take a drink and to invite some revelers to join them. Amidst all the drunkards, Iago will lead Cassio into committing an action that will disgrace him.

How is Iago a manipulative character?

Iago manipulates the other characters of Othello by preying on and triggering their individual doubts and insecurities. He implies to Othello that his wife, Desdemona, is having an affair with Cassio, but, importantly, he makes his implications sound hesitant so that Othello is more inclined to believe him.