Waterdeep:Sim

Sim is a simulacrum of Halaster Blackcloak. He somehow gained independence and distinct sentience from the Mad Mage, and was recently trapped by Erelal Freth, matriarch of House Freth, who believes him to be the original. Erelal forced Sim (who, again, she believes to be Halaster) into a marriage he doesn't want, in a bid to become ruler of Undermountain.