Well, Macbeth only enters the play as a character in Act 1 Scene 3, so he cannot actually behave in the first two scenes. However, the presentation of Macbeth's character in Scene 3 is different from that which is presented in Scene 2. In Scene 2, the Captain reports to King Duncan all that has occurred during Scotland's battle with Norway. The Captain says that Macbeth has fought valiantly and that his character is honorable; Duncan agrees and decides that he will give Macbeth the title of Thane of Cawdor. Here, Macbeth is portrayed as an ultimately loyal character. However, in Scene 3, when Macbeth and Banquo meet the witches and receive the prediction, Macbeth is quite taken by the promise of greatness. Banquo is untrusting of the witches, but Macbeth's greed and ambition compel his desire. Here, Macbeth is not the selfless, loyal character that is presented in the earlier scene.