I don't mind him trying to drink my blood, and I usually play characters compassionate enough to allow him to, so the first part leading up to it all, I'm totally fine with. And in theory I'm fine with the possibility of him killing our character. The problem is, the game keeps going. And we either have to play without our main character, or, more likely, we use the weird undead thing to bring them back. And then he's an utter asshole about it. I think that all undercuts any gravitas the moment could have had. And it only further cements Astarion as an utterly selfish asshole, rather than a complex character. Him killing our character should be a non-standard game over, with an ending slide and then we have to resume. Instead we get this bizarre situation instead that makes keeping Astarion in the party afterwards a decision that pretty much no character would be able to justify. Plus, none of the other companions react to it, when logically they should be pissed off and either drive him away or kill him outright.