Jacob is the man or spirit The Others all aim to serve. He is the one with whom Alpert is able to communicate and the leader of The Others at any given time is said to be able to communicate with him. Jacob is also the fraternal twin of The Man in Black, the evil doer who seems to cause all kinds of trouble on the island. Jacob is able to leave the island in some form and had made contact with each of the main survivors of the crash before it happened.