The characters and atmosphere in Act 2, Scene 1 of Macbeth are portrayed through the language Shakespeare uses and through contrast
Banquo and Fleance are up and awake in the courtyard on a starless night, reflecting the state of evil that has taken hold in the play
Lady Macbeth and Macbeth call for the darkness to hide their intentions, as they do not want the stars to shine upon their deeds
The hidden stars suggest that the course of action has been decided on and cannot be reversed
Banquo, like Macbeth, is troubled by the witches' prophecies, but unlike Macbeth and Lady Macbeth, he looks to merciful powers for help rather than evil spirits
Contrast between Banquo and Duncan:
Duncan was effusive in his praise and lavish in his compliments, while Banquo is on guard and asks for his sword when he hears someone approaching, showing his suspicion or fear
Macbeth subtly hints at a future event to Banquo, suggesting that if Banquo sticks with him, he will benefit from it
Banquo's response indicates that as long as he doesn't lose honor or have to change his allegiance to the king, he will listen to what Macbeth has to say
Macbeth's hallucination of a bloody dagger leading him towards Duncan's room is a symptom of his troubled state of mind, not a prompt towards the act of killing
The hallucination is a product of Macbeth's imagination, showing the mental pressure he is under and his full decision to follow the evil path