Iago's deception of Roderigo. What "show does Iago put on for Roderigo? What are his real intentions in regard to roderigo? How do we find out about them?

Iago has Roderigo poised and ready to pounce on Cassio, and kill him; if either of them is killed, it is to Iago's benefit, although he would like to have both of them disposed of, so that his devices might not be discovered. Here Iago sums up using the pathetic Rederigo in an aside to the audience,

"I have rubbed this young quat almost to the sense,

And he grows angry. Now, whether he kill Cassio

Or Cassio him, or each do kill the other,

Every way makes my gain."