You are exceptional good at 'dominant' bottoms, characters who submit entirely on their own terms. I don't think I commented when you wrote Drace as such, but this reminded me: though the dynamic in that, and this are not otherwise similar.
More specific to this story, I've wondered if Vayne had Bergan attend him in the role Drace seems to perform for Larsa-- and while this is perhaps not where my mind first went with that, it is a very plausibly Archadian extension of those politics. You almost make me pity Bergan, since all of Vayne's affection is for a leashed hound, but I suspect he'd rather take the pleasure in the moment than worry about tomorrow's trap.