can someone interp the exchange between Macbeth and banquo so that i can know why Macbeth's is disappointed

Question

by banquo's answer?


(macbeth)if you shall cleave to my consent , when tis it shall make honor for you

(banquo) in seeking to augment it , but still keep my bosom franchised and allgiance clear i shall be ounseled.

Answer 1

You have to go back to the prophesy of the three witches, who foretold that Macbeth would be king, and Banquo's descendants would be as well. Having seen his own rise come about as predicted, Macbeth is troubled as to how Banquo's family will replace his own, and this is what he wants to speak of to Banquo.

When Banquo says "keep my bosom franchised and allegiance clear"; he is saying, "We can talk, but my heirs WILL be kings."