"What beast was't then, that made you break this enterprise to me?" - Lady Macbeth
Euphemism for murder - no morals + sees it as simply a job
Beast - shows unpredictability of both characters
Wants more power yet too cowardly to commit heinous acts herself
Calling Macbeth unmanly to manipulate him + gaslighting him
First sign of shift in relationship - "you" is more distant than "thou"