Goodness this was glorious!
The sex delicious, of course, but as others have said, the characterizations and plot are what make it.
And the setting, too, really. It had a Regency feel to it, which was lovely.
As a/b/o dynamics are not my kink, I wasn't sure if I would get it, but you made it an integral part of your universe and you made it work beautifully, so bravo!
This is some fabulous writing!