When the witches predict that he shall be king, Macbeth does not think that he should do anything about making the prophecy come true: "If Chance will have me king, why Chance may crown me without my stir." However, when King Duncan places an extra obstacle in his way by naming his son, Malcolm, as his successor, Macbeth realises that, if he is to be king, then he must kill Duncan: "The Prince of Cumberland! That is a step on which I must fall down, or else o'erleap. Stars hide your fires, let not light see my black and deep desires." this prove that he has got an evil side.
Although Macbeth wants to be king, he does not wish to kill Duncan, and he thinks aloud to himself of his reasons: "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, not bear the knife myself." Macbeth does not want to kill Duncan because he is his king and close relation, and because it is his duty as host to protect him. This shows that he is not evil. If he were, his kinship and duty to the king would offer no hindrance to his decision to murder him.
After murdering Duncan, Macbeth is agitated and frightened. He forgets to place the daggers near Duncan's guards as he planned to, and is too afraid to go near the place of murder to correct the mistake: "I'll go no more. I am afraid to think what I have done; look on't again I dare not." Macbeth wishes to wash his hands of Duncan's blood, and the deed, but believes that no amount of water could remove all the blood. He regrets killing Duncan, wishing that he would wake from his sleep of death: "Wake Duncan with thy knocking! I would thou couldst!"
Lady Macbeth, on the other hand, is calm immediately after the murder. She does not appear to be at all worried about being caught, believing that, by cleaning their hands of blood, they are cleaning their hands of the deed: "A little water clears us of this deed." And she fixes Macbeth's mistake by placing the bloodied daggers near the guards so that they are blamed for the murder.
Soon after the murder of Duncan, Macbeth and Lady Macbeth's relationship begins to change. During the planning of the murder, Lady Macbeth is in charge, instructing her husband on what to do. After hiring the murderers to kill Banquo and Fleance, Macbeth tells his wife to "Be innocent of the knowledge, dearest chuck, till thou applaud the deed." showing that he is beginning to take control, plotting on his own and not even telling his wife what he is planning to do.
He has come to distrust everybody, especially Macduff, even to the point of hiring spies, and intend to kill any who get in his way: " There's not a one of them, but in his house I keep a servant fee'd ... For mine own good all causes shall give way." Macbeth is worried about the consequences of his actions. He is afraid that nature will somehow find away to avenge the murders that he has committed: "It will have blood, they say; blood will have blood." Macbeth soon realises that, if the witches told the truth, then all that he fought for will go to Banquo's sons instead of his own: " For Banquo's issue have I filed my mind, for them the gracious Duncan have I murdered, put rancours in the vessel of my peace, only for them." This realisation frustrates Macbeth, and makes him even more determined to survive. Macduff leaving the country before he has a chance to kill him also frustrates him. If he is evil in this play at all, it is now, when he takes out these frustrations by having Macduff's family killed. Macbeth is no longer killing for entirely selfish reasons. He is now like a soldier, killing for survival and what he has fought for but some people might argue that he’s just a murderous thug.
The last time that we see Lady Macbeth in command is at the banquet in Act III. In this scene, Lady Macbeth tries to protect and cover up for Macbeth by excusing his behaviour as a fit when Banquo's ghost appears to him and he addresses it in terror. The next time we see her is in the beginning of the last Act, and she is far from the confident, calm person that we see in Act I. She has begun sleepwalking, and is obviously tormented by the murders that she has had part in. Earlier, she thought that a little water was all that was needed to wash her hands of Duncan's blood, but, while sleepwalking, she thinks that her hands are covered in blood that cannot be removed: " Yet here's a spot…Out, damned spot!’ here, she is turning mental.
Believing in the witches' prediction that "none of woman born" could harm him, and believing that all men are of woman born, he is unafraid of Macduff. When he finds that Macduff was born by caesarean, and therefore is not, in the usual sense, of woman born, he realises that the witches have tricked him. He knows then that, as the witches predicted, Macduff will kill him, but refuses to surrender. This reminds us of the fearless soldier of the first Act and shows that he is not afraid of death, and that he knows that he is about to pay for his mistake. By the attempted kindness of sparing Macduff his life, and the courage he shows by fighting to his death, we see that Macbeth is not a butcher, but a good man with the tragic flaw of ambition.
It is clear by their behaviour that Macbeth and Lady Macbeth are not evil. Lady Macbeth's obvious suffering and regret, shown by her sleepwalking and suicide, and Macbeth's fighting to his death, like the fearless soldier in the first Act, prove that Malcolm's describing them as "this dead butcher and his fiend-like queen" is unfair and inaccurate.