I absolutely love what the show did with relationship power dynamics throughout S3, and particularly what it did with Klaus and Stefan. Klaus is the boogeyman and the seducer and the scapegoat and the shadow self, and his control over Stefan swings from fine-tuned manipulation of Stefan's guilt and shame complexes to the worst excesses of his Hulked-out hybrid self to compulsion to, yes, crackling chemistry. The Stefan/Klaus power play works so perfectly because it was so richly contextualized - we see where and how brutally Klaus learned to play these games, and we see Stefan (within the space of episodes and sometimes single scenes) swing between being victim and victimizer. That's a high-wire act the show went for, and I can't wait to see it play out into next season.