The first scene starts with Banquo voicing his suspicions about Macbeth killing Duncan in order to become the King. He is aware that the witches had prophesized that his sons would become Kings. But he doesn't let this thought obsess him. He is capable of controlling his thoughts and checking his ambitions unlike Macbeth which sets the two apart.
Macbeth enters with the others here. He announces that Banquo is to be the chief guest of the royal banquet he's hosting tonight. Banquo promises to come but not until later after he has returned from his ride with his son, Fleance. …