While the witches appear to have great skill at prophesying, it's not certain whether their prophecies are preordained. If not, do they simply encourage Macbeth to become active in constructing his own fate? It is perhaps part of Macbeth’s character to shape his life according to the predictions – whereas Banquo does not. This might explain why the only prophecy not realized by the end of the play relates directly to Banquo and cannot be shaped by Macbeth (although Macbeth would also have little control over the “Great Birnam Wood” prediction).
Macbeth has been compared to Shakespeare's Antony and Cleopatra . Both Antony and Macbeth as characters seek a new world, even at the cost of the old one. Both are fighting for a throne and have a 'nemesis' to face to achieve that throne. For Antony, the nemesis is Octavius; for Macbeth, it is Banquo. At one point Macbeth even compares himself to Antony, saying "under Banquo / My Genius is rebuk'd, as it is said / Mark Antony's was by Caesar." Lastly, both plays contain powerful and manipulative female figures: Cleopatra and Lady Macbeth.