And not just Enor; the Empress and Girard-the-Booby-Trap also had dark colour on light colour, as I keep pointing out.
While, accordingly, I still think that the bubbles indicate draconic heritage (I'm thinking dragons or half-dragons), there is another possibility as well: they might be giants. Storm giants would be my first guess, since they are somewhat more sophisticated than most and they can levitate under their own power.