"Death is my will."
It's hard to determine if this creature had even once been human, or is the product of a disturbing experiment.
Little is known about Pestilesa's past. Though obviously she was some sort of thief or brigand before falling to the Scourge, as well as a skilled chemist. She has retained part of her will afterwards.
Pestilesa now serves Varimathras faithfully, of her own desire, as well as his own influence.