Yukarifan

Once you finish ToB, you have the choice of becoming a god (and giving up your mortal life) or a mortal (your Baal-esence is taken from you).However, the only explanation about your half-sister Imoen is some encounters with Elminster,maybe forming a thieves' guild or some other half-described possibilities (which are rather pathetic or do nothing to explain her future).

What is never explained is what happens to Imoen as a Baalspawn. Does she just lose her Baal-taint becoming an ordinary mortal? Is she presented with a similar choice, or something in between?