(...) it's almost like light switch was flipped, and then he was an absolutely evil degenerate.
It's understandable for him to be overjoyed when all of his plans succeed and he manages to execute his perfect revenge. He waited 200 years to get it. Plus, he feels an intense rush of power from the ritual - he's practically high then. Just because he talks about wanting to do some things, doesn't mean he will follow through, he's always free to change his mind. He does relax later though and Tav can even sway him in some ways at the end.To be honest, there were multiple instances throughout the game where the darker side of him was emerging. I think he was keeping it supressed so as to not alarm Tav, while fishing for their reactions to see if they were similar to him. That conversation where he mentions Tav is naive to the ways of the world but they have potential and tries to find out if they'd be up for some world domination is very telling. To me, as ascendant he simply unleashes his shadows when he sees that Tav is willing to do anything for him, believing they will condone this side of him and join him as his kindred soul.
But if someone sees him as a danger to the society that needs to be eliminated after the final battle, they should also have that option ingame.
Originally Posted by t1mekill3r
That's what happens to someone who becomes a true vampire in dnd. The game tells you that in Act 1. There is a reason why ascending is the "bad" ending for Astarion's personal quest. Doesn't matter what kind of person he was before.
True, but since he's ascended these rules may not necessarily apply to him. He's a whole new being. I really wish Larian expanded on it and fleshed him out more post-ascension.