I wanted to talk about the gullibility of Roderigo. Iago’s true motive is unclear, it’s clear that he has a deep hatred for Othello, he tells Roderigo this is because Othello didn’t promote him to Lieutenant, and he says he suspects his wife Emilia and Othello had an affair in his soliloquy at the end of scene 3.
“I hate the Moor,
And it is thought abroad that ‘twixt my sheets
‘Has done my office”.
But in the next line of this soliloquy Iago says he doesn’t know if this is actually true, but says he’ll act as if it were only to fuel his hatred for Othello for.
“I know not if’t be true,
But I, for mere suspicion in that kind,
Will do as if for surety’
So, Iago’s real motives are not explicitly stated, there’s no evidence to back up any of his claims and he has already stated that he is selfish and self-serving, and he is willing to lie to himself to intensify his feelings of hatred. His masterplan involves lying and manipulating pretty much every character, including Roderigo who is really susceptible to his lies. In the beginning of act 1 Iago openly tells Roderigo that it’s in his nature to lie, and that he isn’t who he pretends to be. Roderigo is so consumed with trying to win Desdemona’s favor that he doesn’t pick up on this, or even question if he himself is being manipulated. Iago also tells him he hates Othello too because he wasn’t promoted, but this may be another lie to convince Roderigo that he has some logical motives for hating him. He also convinces Roderigo to sail to Cyprus, playing into Iago’s plot. Roderigo is really blind to this manipulation because he thinks he has a chance with Desdemona, and is basically a pawn to Iago.