What effect does Macbeth have on others in William Shakespeare's Macbeth?
Macbeth undergoes a dramatic change in William Shakespeare's Macbeth, and when he changes, the people around him react to him differently.
When Macbeth is a soldier of the king, his enemies fear him as he is a ferocious enemy.
For brave Macbeth--well he deserves that name--
Disdaining fortune, with his brandish'd steel,
Which smoked with bloody execution,
Like valour's minion carved out his passage
Till he faced the slave;
Which ne'er shook hands, nor bade farewell to him,
Till he unseam'd him from the nave to the chaps,
And fix'd his head upon our battlements.
Macbeth is a fearless warrior, and the effect on his enemies is obviously gruesome and violent death.
When Macbeth meets the witches, they are unmoved and unimpressed with him. They greet him with their prophecies, but when he asks them to stay they do not heed him in the least. Macbeth has no effect on them; on the contrary, they are the ones who have a dramatic effect on him.
Duncan is moved to praise Macbeth for his valor in battle. He appreciates Macbeth's loyalty and fierceness on the field of battle, and he expresses that to him. Of course, Macbeth is moved by the king's words--but not enough to keep from killing him, of course.
Macbeth has several effects on his wife. He makes her quite happy when he sends her a letter telling her of the witches' auspicious predictions; however, when she senses that he does not have the necessary resolve to steal the throne through murder, she is disgusted with him. When Macbeth fails to leave the bloody knife with Duncan's body and then expresses his guilty conscience; when he seems to be acting crazy at the banquet, she is disgusted again. While we do not know if this is typical of their relationship, it is certainly how Lady Macbeth feels about her husband in this play.
Macduff despises Macbeth. While they seem to be friendly enough when the discover that Duncan has been murdered, it does not take long for Macduff to distrust Macbeth. He does not attend the banquet King Macbeth invites him to; instead he goes to England to recruit Malcolm and some English troops to go kill Macbeth--which he does.
Banquo is not afraid of Macbeth, even when he probably should have been. He and Macbeth think the prophecies are kind of a joke at first, and their relationship does not seem particularly strained even after Duncan's murder. Banquo does have a few suspicions about what might have happened, but they are not enough to feel as if his life is in danger. It is a deadly miscalculation on Banquo's part.
When Macbeth is its king, the country is afraid of Macbeth. He has spies everywhere because the only way to keep the throne once he gained it the way he did is to live and act in a constant state of paranoia and fear, which he does. The Scottish citizens pay the cost.
The effect on his servants is clear in the last act of the play; when he needs to mount a defense, there is virtually no one left to fight with him. Though they stayed for a long time out of fear, when they had a chance to switch sides and fight against him (if not literally then by not fighting with him) they did it.
Clearly Macbeth before the murder of Duncan is an admirable man. His ambition compels him to take actions (murdering Duncan and others) which cause everyone to either fear or despise him.