He's still not used to the idea of being a prince, even if according to the laws he is one. He had been one his entire life, in fact, though he didn't know it. It explains a great deal of things as well. Which he's not going to dwell on right now; he's had time to consider them already.

He raises no objections to his mother -- his mother! -- calling him such. It's what he was expected to be, after all, and he's just enjoying the fact that he finally has a mother. He wouldn't exist without her. She can call him whatever she wants.

"You don't need to apologize for that...mother." For the first time in his life he tries that word in reference to himself, to an actual person with an identity instead of just someone who must have existed because he does, and the feeling is so overwhelming that he can't stop the tears from welling up in his eyes.