One of the things Jamie is not aware of is that he actually needs others. He's self-reliant, self-sufficient, and he has a pretty good image of himself. Of course, to grow means to change, but how willing is he?
I must point out something, because your comment made me think I didn't make things clear enough in the text. The one with the brother is actually the 'antagonist' - let's call him that for now - and when there are such paragraphs without names being mentioned, those feature him, not Jamie. Sorry for the confusion.