How does Perlith mock Aerin when she asks to go west with her father and his men in the novel, The Hero and the Crown?

When Aerin asks to go with her father and his men, Perlith rudely says that Aerin has been spoiled and that she should have been slapped, not encouraged, years ago. Then he says that Aerin doesn't have royal blood in her veins. As he leaves, he mockingly calls Aerin Dragon-Killer.