I agree with you, OP. Not only is it squicky, the encounter is a bit nonsensical. If you accept but don't pass the persuasion checks he ends up killing your character, so if your character didn't wake up to find him creeping in the first place, was his original plan just to feed on one of his allies, at the risk of killing, right in the middle of camp? Though, it's not like anyone jumped to the defense when you spotted him anyway... sleepin on the job :P
Something else I recall when you catch him is that he says something about having to do it this way because he needed your trust? Which doesn't make any sense. I also think it's a good idea if the scene were changed to be the character seeing Astarion sneaking out of camp again (which the camera shows for the boar encounter) and they find him snacking on animals.
To clear up: He doesn't state he needs the trust of a person to suck their blood. He merely asks you to trust him enough to let him bite you because he is desperate. I think the persuasion roll is not about what he intended to do. I felt like the scene was:
- He truely intends to only get a sip of you
- You (potentially) agree to that
- Against his prior intention, he loses control over himself (Maybe the image of "I'll only eat 5 chips" and ending up eating the whole package helps to get the idea?)
- With the persuation check, you try to make him snap out of his frenzy
The persuation check was a 1 for me, so I wondered why I had to roll at all. But by now I realize your modifiers are countet against the target roll and I had high charisma and proficiency in persuation. Never the less, it's still a low roll that should tighten the idea that he intends to play along, so that's why I considered it "reminding him" rather than "having to convince him" to stop.
