In the Shakespeare play, Macbeth, Duncan is brutally murdered by one of his own lieutenants. The particular death was not only bloody, but it was a betrayal, so the natural reaction of anyone would be that of both disgust and loathing. To kill one's friend, especially after he's given him all sorts of rewards and promotions makes one instantly dislike Macbeth. Then, when one considers the attitude of his wife, then it is doubly interesting to watch them watch the benefits of their own misdeeds.
