A bit eccentric in a silly way. He was sent down from Hell to cause chaos- aka killing Job's children, his goats and burning his house. Instead, Bildad ended up just turning the children to lizards to keep up the appearance of "killing them" (later on turning them back to humans and pretending those were Job's 'new children'), miracled the goats to become crows, etc: basically, Bildad/Crowley is against the killing of innocents and animals. He kept up the ruse of being evil to other demons/angels, including Aziraphale. Internally he does have a darker side and can appear quite menacing when he wants too. A bit mischevious