In most stories, the reader or audience identifies with the main character. However, if the main character displays signs of mental illness, the reader is often turned off and alienated. Through their actions and signs of mental illness, Macbeth and Lady Macbeth lose the reader’s sympathy.
The audience is generally sympathetic to Macbeth and Lady Macbeth at first. When Macbeth is told he will be king, we are happy for him. When he is disappointed that he is not chosen as Duncan’s successor, we feel sorry for him. We also pity Lady Macbeth, or at least relate to her, when she gets his letter and wants her husband to be king. To want to be king is a natural desire. We understand it.
When Macbeth arrives at the castle, we start to feel less ambivalent toward the couple. Lady Macbeth sounds cruel, violent, and downright mad when she describes how she would bash her newborn child’s brains in.
I would, while it was smiling in my face,
Have pluck'd my nipple from his boneless gums,
And dash'd the brains out, had I so sworn as you
Have done to this.(65) (Act 1, Scene 7, enotes etext p. 24)
This is crazy talk, but it is not the kind that is going to earn the reader’s sympathy. At this point, the reader begins to doubt Lady Macbeth’s sanity and get a feeling of impending doom. We realize that she is going to try to goad her husband into murder.
We hang on with Macbeth a little longer. We see him struggling, trying to decide if he should follow his wife’s wishes.
He's here in double trust:
First, as I am his kinsman and his subject,
Strong both against the deed; then, as his host,
Who should against his murderer shut the door, (Act I, Scene 7, p. 22)
This is one of the last sane things Macbeth says. Unfortunately, Macbeth really begins to lose his mental sanity once returning home. He imagines the floating dagger that makes the reader determine that yes, he is crazy. We no longer respect or feel any appreciation for either Macbeth or his wife.
After Macbeth kills Duncan, we do not root for him. He sees Banqo’s ghost, and we feel gratified. We want him to be punished by his hallucinations.
In the last act, the reader may feel some sympathy for Lady Macbeth when she sleepwalks and imagines her bloody hands, and we might feel some sympathy for Macbeth when he ponders human frailty.
Life's but a walking shadow, a poor player
That struts and frets his hour upon the stage
And then is heard no more. It is a tale
Told by an idiot, full of full of sound and fury,
Signifying nothing. (Act 5, Scene 5, p. 84)
However, this momentary rush of guilt on both their parts is not enough for the reader’s sympathies to fall back in with them. The mental illness they have reflects itself in violence and betrayal. We cannot wait for the curtain to fall.