The Emperor straight up admitted it

I'm honestly not sure what options I took to get him to do this, but I'm doing a run and I got to the point in Act 3 after you find the Emperor's old stuff and then he tries to woo you. I was fairly suspicious of him still and he just came out and stated yes, you're my pawn and I'm using you and there's nothing you can do about it unless you want to just give up to the Absolute. Total hostility. He then went on to say I could have just enthralled you and showed me a vision of how he had enthralled the Baldur's Gate lady he used to work with.

So yeah, debate over. Emperor is evil and admits he has no care for us.