I think the same could be used for AA, he has his evil smirk in the beginning but once the kiss is done he has a playful smile. I can almost say that is what he is doing with bite kiss, I think that is why that specific kiss is my favorite out of all AA and UA kisses.
After the biting finishes he gives the player character a single sweet kiss, the player character leans into it and gets a face slap as a reward. There is nothing playful about this, he enjoys being cruel to the player character and that's it. Which is why I think it is such a horrible idea to ask for this kiss for the unascended route as well, which does not have any kind of "perhaps you are enjoying to degrade yourself" framing, but is a partnership between equals as stated by the dialogue post Cazador.
