What can we infer about Banquo and Macbeth based on their reactions to the prophecies of the witches?
Their immediate reactions during the encounter are not too dissimilar. Banquo has less to say either to them or about them, but this suggests that he is a wiser, more self-controlled man. He seems to be a thoughtful, taciturn, serious man in all his appearances in the play. After all, if his children are going to be kings he has plenty of time to wait. It appears that at the present time he has only one child, the boy Fleance. The children who are to be kings may not even be born yet. So Banquo is more philosophical, if not skeptical. With Macbeth, however, what the witches have prophesized corresponds directly with what he and his wife have been thinking and talking about. His reaction is much more intense and overt. He almost shouts, "Stay you imperfect speakers. Tell me more" and continues to question them for eight more lines. (1.3.73-81) Banquo must notice Macbeth's strong reaction and wonder about it, especially after Duncan is murdered. Both men seem to believe what the witches have promised them.
The three witches are intended by Shakespeare as evil characters, especially as seen from a Christian perspective. Banquo reacts as a strongly positive moral, and Christian, character should react, by distrusting the evil hags, doubting their prophecies, and believing that no good can come from listening to evil. Although the prophecies do turn out to be factually correct, on a moral level, Banquo’s reaction is justified by the evil caused by Macbeth’s listening to the prophecies. Macbeth, who is extremely ambitious and lacking in strong moral or religious sense, believes the prophecies and tries to use them for his own advantage. His willingness to consort with and take advantage of evil show him to be a morally contemptible character.