Sladis was always fascinated by the Underdark, but the madness spread by the demon lords broke his sanity. However, it was not too late for him to be cured.
Sladis was one of the students of Morista Malkin in Gauntlgrym. However, at the start of Rage of Demons, he was driven mad and he disappeared into the Underdark.
Driven by madness, he started to kill and eat other humanoids he encountered until he arrived in Mantol-Derith. There, Sladis worked as a guide to Menzoberranzan, Gracklstugh, Neverlight Grove, and Blingdenstone