As for the scene where Grayson felt Carlotta should have been intercut reacting to Quentin and Angelique's lovemaking, well, it might be best that DC never went there because I don't know if the audience was really ready for that.
I don't know whether Sam Hall did this deliberately, but I am always struck by the fact that Carlotta is a female form of the name Charles, A's original lover in 1810; and Drake refers to dragons, to cthonic underworld energies, to things potent yet unseen...