He thinks that Macbeth is a "good guy", Fleance killed Banquo and Duncan's sons killed the king.
Your teacher probably wants to hear ambition, and that is correct. It is also natural; anyone would have their ambition encouraged by being told that they are going to be king, especially if there is a reasonable possibility it could happen. Being told that you will someday become President or Prime Minister might encourage anyone to develop political ambitions.
Haiti