In some of his appearances, Jacob has shown supernatural powers including immortality, healing, omniscience, and changing peoples' destiny to suit his goals.

Due to these powers, he has had a considerable influence on the lives of several main characters including Jack Shephard, Kate Austen, John Locke, James "Sawyer" Ford and Hugo "Hurley" Reyes.

Jacob's earliest chronological appearance is in the sixth season episode "Across the Sea" where he is born to a Roman woman named Claudia, who was shipwrecked on the island sometime in the 1st century.

In revenge, Jacob threw his brother into the cavern which emitted the light, an act which he was told by his mother would lead to a fate "worse than death".

[2][3] Jacob's next chronological appearance was in the sixth-season episode "Ab Aeterno" set in 1867 when Richard Alpert became shipwrecked on the island.

However, Jacob convinced Alpert to join him and granted him immortality, told him the true nature of the island, and made him his spokesperson.

Over time, Jacob had Richard recruit people from the mainland to become part of his group such as Juliet Burke and Tom Friendly.

[5] At some point before the crash of Ajira Flight 316, Jacob recruited his long-time bodyguard Ilana Verdansky to help protect the remaining six candidates: Jack, Sawyer, Jin & Sun, Hurley, and Sayid.

In turn, Verdansky got a group of others including an associate named Bram, to facilitate the return of the candidates to the island on the Ajira flight and to act as Jacob's bodyguards.

At some point in the past, Jacob compiled a list of 364 candidates (virtually everyone that has visited the island since at least 1988) on a glass dial in a derelict lighthouse that only he is aware of until he instructs Hurley to take Jack there in a successful effort to show how important the latter is to his plan.

The producers, particularly Damon Lindelof and Carlton Cuse, have implied that the character was inspired by Aslan from the Chronicles of Narnia, showcasing his god-like powers and kind nature.

Lindelof also stated that he and co-creator J. J. Abrams had planned for the concept of light and dark to eventually be personified by Jacob and Man in Black, referencing the scene in Pilot, Part 2 where Locke explains the game of backgammon to Walt Lloyd.

In the episode, "What They Died For", Jacob appears before a burning bush and Jack accepts his responsibilities, mirroring Moses from the Book of Exodus.