If you don't know, where the drow is:

She is in a room to the left if facing the throne

Good luck.

I actually try to romance Astarion with my Durge (Dark Urge) this playthrough, since the writer of Astarion did write the Durge too and gave them extra scenes - it is very easy as Durge to get a lot of approval with Astarion very soon. But of course it is a very dark background.

"We are all stories in the end. Just make it a good one."

Doctor Who