Calm yourself Roderigo. We should see to it their marriage be ruined at their own fault.
Honest Iago! How could you not tell me Othello married the love of MY life, Desdemona?
We both need to get back at Othello in our own ways. Your love being stolen, and my position as a higher soldier was stolen as well!
You are promoted great Cassio
Turning Desdemona's father against Othello should work? No we need something fool proof! Ah, I've got it!
I SHALL HAVE OTHELLO EXECUTED!
First we have Othello lose all trust in Cassio. In some way like a staged fight, then convince Othello that Cassio is not to be trusted around Desdemona! Then we find a way for Othello to catch them in the act of adultery.
After all this persuasion using my title as honest, Othello will go in a blind rage towards everyone. And before then I'll ensure Cassio will be demoted and I can take his place! Othello will believe this was all a tragic series of events.
There is no way this plan can fall apart, are you with me?