In Act 1 Scene 3 of the Shakespearean play, Macbeth [c. 1014-August 15, 1057] seemed to have the character and show the attitude of a colleague towards fellow General Banquo. He discussed the events of the day and appeared to respect Banquo's opinions. But then they met the three witches, and then the noblemen Angus and Ross. What the witches predicted began to be verified by what the noblemen told Macbeth and Banquo. At that point, readers and viewers suspected that the friendly competition between Banquo and Macbeth might turn sour.
That respectful competition between friends indeed could be seen to have soured, in Act 3 Scene 1. The scene began with Banquo accusing Macbeth of having gained the predicted royal title by foul means. What could be the consequence other than fatal for a friend who accused a murderer of murder and whose family line was prophesied to take over the throne from the murderer? As soon as Banquo left, Macbeth indeed called in hired murderers to kill his friend and his friend's son. The friendly competition had ended. The unfriendly competition had begun.