Karlach on the other hand says she was a prisoner of Zariel. I don't believe she mentions selling her soul. Anyway, she is a Tiefling, not a devil. And she has a tadpole.
She doesn’t but with deductive reasoning, you can make the assertion she either sold her soul or was in fact someone who worshipped devils and died. That would take your soul to Avernus in the afterlife. Her being a prisoner can be considered embellishment on her part.
Either scenario doesn’t make her innocent.
Also I never got the implication that she has a tadpole. Your character can make mind links and other mental abilities with non-hosts, such as using the power to bypass certain dialogue with the goblins. The game never explicitly says she’s infected.
