She also has a line where she outright states that the Sharran circle in Baldur's Gate wiped her memories in order to have her carry out her mission of obtaining the Gith artifact and that upon completion of this mission her memories will be restored, so that theory is confirmed now.
Wasn't a theory, it's already available in the game if you play a Cleric of Shar, people just don't believe it because it doesn't match their theory of what she is.
Oh alright then. If people believe she is a brainwashed Selunite then that is not really out of the question yet. We don't know what memories the Sharrans in Baldur's Gate erased.
