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. 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 ... he should be Noble after all.
