In Act III Scene ii, what role does darkness have?
Macbeth uses the darkness to carry out his murders. The night of Duncan's murder he was walking the darkened halls and runs into Banquo. Banquo does not recognize him at first. In this seen , he discusses the evil that comes out at night, "Good things of day begin to droop and drowse,While night's black agents awake to seek their prey." In this way, we can see that Macbeth is the black agent, and Banquo is his prey.
At this point in the play, we notice that Macbeth is beginning to make plans separate from his evil wife. He is coming into his own as an evil murderer, and no longer needs the strength of his wife to carry out his diabolical plans. His character darkens with each murder, and becomes darker still as he awaits the prophecies of the witches to come true.
Lady Machbeth and Machbeth are trying to survive among nightmares.Their fears are coming out and surrounding their ruin,based happiness and unfair royalty. Dark represents both the troubles they are facing under the heavy cost of devil murder and the consequenses they are going to face,thus learn the real message which the witches conceal behind their prophecies.