In Act I, Scene III, the witches come on the scene and prophecy to Macbeth. When the witches give their prophecy to Macbeth, Banquo's reaction is one of jealousy or envy. He asked, "what about me?" No doubt, Banquo is happy for Macbeth, but he really wants a prophecy for himself. In Act I, Scene III, he asks Macbeth why he seems startled by the beautiful prophecy. Then he addresses the witches with his own questions:
Good sir, why are you startled, and seem afraid of
Things that sound so beautiful? In the name of truth,
Are you fantastic beings or indeed what
You look like? You greet my noble partner
With current grace and great predictions
Of having nobility and of the hope to be king,
that he seems carried away as well. Only you don’t speak to me.
If you can look into the future,
And say what will happen, and what will not,
Then speak to me, who doesn’t beg or is afraid of
Your favors or your hateful spells.
Indeed, Banquo wants the witches to prophesy over him. He claims that Macbeth's prophecy is beautiful and he desires one of his very own.
Then the witches tell him that his sons shall be kings:
Your sons will be kings, even though you will not be king.
So all hail, Macbeth and Banquo!
They tell Banquo that he will be happier than Macbeth. Clearly, Banquo is envious of Macbeth until he hears this good report. No doubt, he is delighted as well as being confused by what he has seen and heard. Banquo begins to question whether or not he has eaten a plant root that made him hallucinate. It is all a dream.
Are you sure we’re talking about what we’ve seen here?
Or have we eaten some plant root
That makes us hallucinate?
This act has left Banquo questioning whether or not it is real. He cannot believe the prophecy of the witches until Ross comes and confirms the prophecy. Ross addresses Macbeth as Thane of Cawdor. Then Banquo knows the prophecy is real.
Of course, later on Banquo questions so many things. He questions whether or not Macbeth has played foully for his position as king. Banquo becomes suspicious about the murder of King Duncan and he suspects that Macbeth has been a part of the murder. Ultimately, Banquo knows too much; therefore, Macbeth has him murdered.
I personaly played Banquo and had to know it inside and out. Banquo immediatly suspects that Macbeth would take advantage and becomes aware of his surroundings, and he becomes suspicious of the withche;s fortune telling. He is envious of Macbeth until he hears that he will be happier than Macbeth and bellieves that he has hallucinated or eaten a strange plant root. But Banquo is curious up until his death of what the fortune reads.