Ok please correct me if I'm wrong here, but there is no good part to Astarion. He is undead. There is no personality or soul left in him. He is an artificially animated meat bag. "He" could not have been tortured for the past 100 years or whatever because "He" ceased to exist the moment he was made a spawn. Kill Cazadore to free him and all you get is Astarion as a full and more powerful undead. The only way he comes back to who he use to be is the use of a Wish spell.
There is no gray here for Astarion, undead are evil and soulless(literally). The only realistic way helping Astarion out ends up is with him turning Tav into his own vampire spawn mind controlled minion once freed from Cazador and a full vamp.
Personally I find Astarion to be the worst written and conceptualized companion in the game.
I think we're going to learn that this is actually not true. All of it. Typical vampire spawn? Yes. But there's more to Astarion than him being a typical vampire spawn.
For 1, he has infernal tattoos on his back. I think he's some sort of experiment Cazador has been playing with, and he received some devil assistance with it. Perhaps the reason the mind flayers took him was because his soul was put back, returned from Avernus where it went when he died, in his undead body prior to the abduction, and now the tadpole has twisted him into something even more unusual. Who knows?
Either way, I think the whole point of Astarion IS that he is not some soulless undead monster, but he has been somehow turned into a half living, half undead being - prior to the tadpole. Why else would Cazador treat him so unusually?
Or he's totally lying about everything and he actually is Cazador, playing with you and making you think he's got a soul. Lol
