I'm just really, REALLY hoping that there's some further plot development coming, because if the Northern Water Tribe leader is the Big Bad, it's going to feel embarrassingly obvious. He's got a blatantly obvious motive, suspicious abilities, and an apparent ambition for power. I would honestly like it if the series gave some perfectly reasonable explanation for all of his actions and had a different reason for unrest in the Spirit World, because otherwise it would just seem like lazy writing to me.