Cruor is an dead imp. Its corpse is in the Chosen's Room in the Bhaal Temple within the Undercity. It was sent to Orin to become her butler but instead, she experimented on it leading to its death.
Cruor was sent to Orin by Bhaal, against her wishes. According to a nearby book, Orin grew increasingly frustrated at the imp praising the way she slaughtered her enemies that she decided to end its life to silence it. Butlers of Bhaal which are no longer needed, for whatever reason, die permanently.
Cruor may be a reference to Cespenar, Bhaal's imp butler from Baldur's Gate 2 which served Gorion's Ward in their Pocket Plane as they explored the limits of their divinity inherited from Bhaal. Some players have found Cespenar's attitude, voice, and lengthy dialogue lines to be annoying.
