Stories can have many characters working on either side (and some working both sides), but your story comes down to a central conflict. For Martin's first book, without going back and reading it again, I'd say the conflict is between Ned Stark and Cercei. Please don't misunderstand me. You should have well-constructed, vibrant secondary characters that contribute in great and small ways. But the central conflict is what drives your story, either directly or indirectly.