Shakespeare develops Banquo and Macbeth’s friendship in a variety of different ways but his main method is to show how well they were friends before they met the witches, but after they met them, Macbeth was willing to give up everything to be King, including his friend. Banquo though didn’t believe the witches and decided to trust in his friend, which was his ultimate downfall.
Macbeth and Banquo together encounter the witches where Macbeth hears their prophecy for the first time. Banquo reacts as a friend would at the sound of Macbeth's good fortune, then seeks to know his own future. Banquo warns Macbeth that the witches could be telling lies and is quick to distinguish their evil plans where Macbeth fails to. Banquo also warns Macbeth, “… oftentimes, to win us to our harm, The instruments of darkness tell us truths…” Here, Shakespeare demonstrates how much Banquo really cares for Macbeth by making him realise the danger of the atmosphere and how he tries to warn Macbeth. Macbeth however is oblivious to this fact and ignores his friend, instead asking the witches to continue talking. This shows how Macbeth has already forgotten about his friendship with Banquo over being King.
When Macbeth murders the King, Banquo’s suspicion grows but he remains loyal to his friend and doesn’t believe that Macbeth would deceive him. Shakespeare uses this on purpose, showing how Banquo doesn’t want to think