Rather than trying to make this scenario make sense, the best choice would be to scrap his introductory scene altogether and have him try a more charming approach. I mean he's supposedly spent lifetimes lulling people to false sense of security, so he should be able to pull off a polite introduction. Edit: Of course any reworked scene should have the option to kill him. At the current state, the character is, among other things, way too murderous to justify his presence in the party as anything but a curious betrayal waiting to happen, unless you overlook his introduction and his rapey feeding habits.
Well, at least he's sort of accurate depiction of what the aristocracy is like.
+1 I found his introduction to be shaky when it comes to execution, but also very off putting. It’s not that he tries to kill us to start with, but that he is miserably transparent and horrible at it. Awkward rolling on the ground doesn’t help the matter. I think I overall would like Astarion better if he was half competent at being manipulative.
