Sebastian is a dedicated butler to Ciel Phantomhive and upholds a strong sense of duty to his master and household. He faithfully follows and carries out every one of Ciel's orders, while ensuring that the Phantomhive household runs smoothly. He does not sleep—for demons deem it as a form of luxury—and thus, he frequently performs tasks for Ciel at night. One of his quirks is that he will always respond to Ciel's demands with the saying "Yes, my lord." Hes (obviously) one of the main charecters and whoreveris casted for him must be able to become and stay Sebastian untill the series is over.