Macbeth lies, while Banquo insists on remaining loyal to Duncan
Act 2, Scene 1 is set in Macbeth’s castle where King Duncan is spending the night. Banquo is there, too, with his son, Fleance. He seems nervous, which is indicated by the fact that he gives Fleance his sword as well as his dagger for protection (2.1.5-6). We also hear that the night is very dark.
When entering, Macbeth presents himself as a “friend” (2.1.13) to Banquo and Fleance. This is the first of two lies that Macbeth gives in this scene. We can tell it is a lie since we know that he is already planning to kill Duncan and is probably ready to get rid of Banquo, too, if he will not support Macbeth. This is hinted when he asks Banquo to be loyal to him: “If you shall cleave to my consent, when ‘tis, / It shall make honour for you.” (2.1.31-32).
The witches’ prophecy stated that Banquo would father a line of kings, which makes him a rival to Macbeth’s own future heirs. This probably explains why Macbeth wants to keep him close.
However, Banquo’s friendly but firm reply shows that he insists on remaining loyal to King Duncan above anything:
So I lose none
In seeking to augment it, but still keep