I don't know enough about FR vampire lore to know, but I thought his line about the wine being sour, which you can taste and have described as rich, was a result of vampires not being able to enjoy food. Is that a thing? from that view point I think his disposition at the party could stem from his feeling alienated from the mortal world, even when he's been lead to behave morally...but it's not really a lot to go on.
I thought the same, that he was describing the wine, and I think the whole enjoying food is a thing, since he said tea isnt really his drink, either hes a coffee man or he just doesnt like tea!
But yeah I do think that he might like getting used to the idea of being a "hero" if you keep taking him on that path!
I need to stop analysing it's still EA