To the both of you I would say this: for the sake of argument, let's assume you guys are correct about your "brainwashing" thesis (which is entirely possibly what Larian has written for her). For me, that still doesn't change much. Even if someone were brainwashed or conned or manipulated into their actions, if they committed evil acts, especially acts that caused irreversible harm to innocent people, they are still very much responsible for those acts. They don't get to use the "i was brainwashed" line to absolve themselves of their culpability. They still have to atone for what they did, which includes suffering harsh consequences for what they did. And note, I very specifically don't say doing good things will absolve them, because it doesn't. Doing good things now does not cancel out the evil things one did previously, because if you killed someone, that is irreversible. Saving someone today doesn't do a damn thing for that person you killed yesterday.
Sorry, I somehow missed your answer there.
But to address this, as far as the background we are given, she and a couple of others where memory wiped and send to recover the artifact. Then we meet her and she doesn't really like evil actions. Thats it.
She is someone who spouts the Shar-is-actually-good propaganda and wears a bunch of Shars symbols. She never adapts her propaganda to gain our trust. By all accounts, she is incredibly suspicious. A good Sharran would not be suspicious, which gives -in my opinion at least- credence to the brainwashing theory. Maybe she was a Sharran before that messed up and this is her punishment. But regardless, she is not a real Sharran Priest, she just thinks she is.
I just noticed that she is actually similiar to Lae'zel in that regard - both spouse propaganda and are blind to the true nature of what they endorse. Which is probably the angle to redeem them (harsh reality shock) and also to corrupt them (ease them into the reality). Lae'zel fits better in her respecitve propaganda line, while Shadowheart rather obviously does not.