"There, in dim firelight, you see him for what he really is; a vampire. A slave to sanguine hunger."
That just sounds like a DM who graduated from the 'tell, don't show' school of storycraft.
So ... How exactly would you do that?
Plenty of ways. Just cut the narrator for one. Had you really not worked out that Asterion was a vampire until the narrator force-fed the exposition to you? They are about to explicitly reveal it through dialogue anyway.
