I do not know much about dragons. Somehow dragons and I have never quite clicked - but I agree they'd certainly come closer to vampires than to the other two groups. Only, they're a bit more complicated because there are several, effectively-independent dragon traditions across the world, making them a more heterogeneous group to begin with. Whereas vampires are generally riffing off an accepted "canon", even when they're departing from it. That ought to permit even greater draconian flexibility, I guess.