My favorite kind of DubCon where its not really very Dub at all. Ruruna is saying "stop" but deep down she's thinking "please keep going". It's the best.
So like are vampires a different species and not undead humans. Because how do vampires reproduce except by turning other humans into vampires. Like what they live for 1000 years and be like how interesting that humans bond like animals.
If it went any further, we'd have to see that awkward moment when the lovestruck human discovers her vampiress master has a totally smooth and featureless crotch.