'I will wear my heart upon my sleeve
For daws to peck at.'
He follows Othello not out of “love” or “duty,” but because he feels he can exploit and dupe his master, thereby revenging himself upon the man he suspects of having slept with his wife. Iago finds that people who are what they seem are foolish. The day he decides to demonstrate outwardly what he feels inwardly, Iago explains, will be the day he makes himself most vulnerable
“Excellent wretch!/ Perdition catch my soul / But I do love thee, and when I love thee not, / Chaos is come again'
Othello seems far more comfortable expressing his love for Desdemona when she is absent. perhaps this is because he is more in love with some idea or image of Desdemona than he is with Desdemona herself. The lines just quoted indicate how much his image of her means to him: if he stops loving her, the entire universe stops making sense for him, and the world is reduced to “Chaos.”