Again you raise many good points! I actually agree with what you've stated but only partly, saying that Astarion (unless I have missed something and if I have please let me know)
Saying he is willing to kill for any reason and be manipulative is maybe going overboard.
[/spoiler] I'm just referring to the time you first find out hes a vampire and he states that he only drinks animal blood, I dont know if he was lying or something, [spoiler]
But if he was really a heartless killer youd probably see more dead bodies or youd see either yourself or your companions dead along the road.
At the moment I think right now hes just doing what it takes to survive which is what many including your own character is doing.
I agree definitely with the red prince similarities, both are definitely pompous and selfish