I'm not so about that. He seems to actively goes out to obey Dresden's orders in the most malicious way possible. He continuously states how much he hates working for Dresden, and to me at least seems to only be willing to work fore Dresden as he is obliged to.
Well, of course he's a jackass about following orders to the letter. He's a Fae. His opinion of Harry doesn't affect his loyalty to Mab. Again, trying to take an order from Harry gets him closer to shaking off Nemesis than anyone we've ever seen.