Originally Kal'dir was a noble in an unknown drow city, but his House was totally destroyed and only he survived. Without allies or resources, Kal'dir wandered for a while in the Underdark until he met a beholder cluster. He was charmed to serve them.
In 1479 DR, he willingly became their emissary to Waterdeep in order to help the new Xanathar, Zushaxx, to establish himself as the new Xanathar. Kal'dir assassinated all the previous lieutenants of the guild. Zushaxx quickly affirmed his rule and Kal'dir was chosen as one of the new lieutenants.
Kal'dir supervised all the guild's activities involving the use of violence: assassinations, extortions, blackmail, and enforcement. He was brutal but efficient. Under Zushaxx's orders, he fomented strife among the other lieutenants.
Kal'dir was naturally charismatic, with a talent for scheming. However, he preferred to remain silent and alone with himself. Thanks to his drow heritage, Kal'dir deferred to the authority of his female peers.