The Amoral Aristocrat
The last full-blooded heir to the once-illustrious Zed Mercantile House in Alabaste, Mercer is known for his cruel detachment. He has ties to slavers in the Sea of Stars and the tribes in the southern wastes, and rumors speak of other, darker agendas. The Zed name has, in recent decades, accumulated no small amount of filth, and it is safe to say that Mercer is to be thanked for most of it.
Mercer has some amount of arcane power, though the source is unknown. Many believe him to have taken an extreme view of the Tyran faith (similar to what some within the Inquisition have), though that may be a rumor he started himself to avoid raising suspicion.
With enough money to purchase whatever a man could want, his motives are simply one more secret Mercer keeps.