Sebastian takes on the appearance of a tall, handsome adult with black hair, reddish brown eyes, pale skin, and black fingernails. The back of his left hand contains the mark of his Faustian contract with Ciel Phantomhive. Sebastian is devoted to Ciel Phantomhive. He faithfully carries out every one of Ciel's orders while ensuring that the Phantomhive household runs smoothly as the head butler. Sebastian is cunning and morally bankrupt, and he has no qualms about lying, cheating, and seducing.