Act 2 Scene 3
A. Cassio reasons that he is on duty despite Iago's pleadings to have a drink. His will is not as strong as his reason and ends up falling for Iago's ploy.
B. Iago as a petty vilain full of spite and incessant scheming. He is Othello's doppleganger. Othello is is principled and open about his grievances. He settles scores in the open like a "man" and a gentleman soldier.
C. We see Othello's tragic flaw. He thinks in black and white. He sees in extremes with nothing in-between. Othello easily falls prey to manipulations about his absolute sense of loyalty, fidelity and honour.
Oh Appearance vs Reality- Certainly Iago's whole nasty plan to inflict upon Cassio and Iago, is dependant on appearance and reality.
