There's a subtle something to Olivia's demeanor, and more to the point the demeanor of those around her. Arthur, brought up in a palace since birth, has a keen eye for it; for the sort of bearing that comes with authority, knowing one may go wherever one pleases (needs to be), and address whomever as an equal -- or lesser. When he approaches her, he nods with a certain amount of respect if without deference.

"My lady."