He exhibited the ability to scan the minds and memories of others, allowing him to confront characters such as Mr. Eko (Adewale Akinnuoye-Agbaje) and Ben Linus (Michael Emerson), with "judgement", and assume the appearances and memories of the dead, such as Christian Shephard (John Terry), Yemi (Adetokumboh M'Cormack), Alex Rousseau (Tania Raymonde), and Locke.

[6] Prior to the twentieth century, The Man in Black's earliest chronological appearance occurs in the sixth-season episode "Across the Sea", which depicts his birth on the island to a woman named Claudia (Lela Loren), whose ship breaks apart offshore.

An unnamed woman (Allison Janney) delivers him and his twin brother Jacob (Mark Pellegrino) but kills their mother and raises the boys herself.

At age thirteen, the twins discover the other survivors of Claudia's ship on the island, and their adoptive mother takes them to a mysterious cave filled with light with a stream running into it.

Jacob visits his brother at the survivors' camp at various points over the course of the next thirty years, during which time The Man in Black comes to believe his mother was right in calling humanity inherently corrupt.

She knocks him unconscious, and then apparently massacres the people in the camp and destroys the well; enraged, The Man in Black kills her with a dagger.

This crew includes Danielle Rousseau (Melissa Farman), who is joined by a time-traveling Jin-Soo Kwon (Daniel Dae Kim).

"[10] On September 22, 2004, immediately after the crash of Oceanic 815, The Man in Black takes the form of Christian Shephard (John Terry).

In the season one finale, "Exodus", The Man in Black attacks a group of the survivors as the monster again; he attempts to drag Locke down a hole, but is stopped by Jack and Kate.

[16] In season four, after becoming enraged over the death of his adoptive daughter Alex Rousseau (Tania Raymonde) by mercenary team leader Martin Keamy (Kevin Durand) hired by Charles Widmore (Alan Dale), Ben Linus (Michael Emerson) rushes to a hidden room below his home at the Barracks, which has an ancient stone door covered with hieroglyphs; there, he drains a small pool that summons The Man in Black, as the monster, to brutally assault the mercenaries.

[17] As some of the survivors are preparing to leave the island, The Man in Black keeps Claire Littleton (Emilie de Ravin) company in the form of her father Christian Shephard, who tells her that The Others took her son Aaron.

[18][19][20][21] In late December 2007, following Ajira Airways Flight 316's crash on the island, The Man in Black, as Christian Shephard, appears to Sun-Hwa Kwon (Yunjin Kim) and Frank Lapidus (Jeff Fahey), informing them of the time travel undergone by the rest of the Oceanic Six.

[8][22] Later, Ben tells The Man in Black, who he thinks is Locke, that he must travel to the monster's lair, which lies beneath the Temple wall, to be judged for his complicity in his daughter's death.

Later, they return to camp where "Locke" speaks to The Others and tells them that they are going on a trip to see Jacob, from whom they take orders but have never met; Richard reluctantly complies.

An emotional Ben then confronts Jacob by asking him why he has been constantly ignored by him for so many years while also expressing how much he has sacrificed and suffered on the island.

Outside, a group from Ajira 316 sent to protect Jacob, led by Ilana Verdansky (Zuleikha Robinson), arrives and reveal the contents of a giant metal crate from the cargo of the plane: John Locke's dead body.

During their walk through the jungle, "Locke" becomes distracted by a young, mysterious blond boy (Jacob in the form of his younger self) and gives chase.

[28] After Jin is taken from camp by Widmore's group so that he can assist them in the assassination of The Man in Black, the latter travels to Hydra Island with Sayid.

Upon returning to his camp, Jack's group—this time led by Hurley (Jorge Garcia)—arrives where they finally meet The Man in Black.

Sawyer then reveals his plan to secretly escape The Man in Black's command and leave the island with Jack, Hurley, Sun, and Lapidus.

An angered Sawyer watches as Jack reclaims his position as a man of faith and refuses to run by jumping into the ocean.

Unbeknownst to them, Widmore broke his deal with Sawyer and locked the group in a cage to protect them from The Man in Black's imminent arrival.

Moments after Sawyer's group is caged, "Locke" attacks Widmore's camp as the monster while Jack arrives and frees his captive friends.

Sawyer then attempts to disarm the bomb, but Jack tells him not to since he has figured out that "Locke" can't kill the candidates himself and wants them to all die together in a "nice enclosed space".

Satisfied, "Locke" leaves the cave, but Jack attacks him, drawing blood, making The Man in Black realize that he just made himself mortal.

[34] This idea was changed by the end of season one, when the character Danielle Rousseau describes the monster as a "security system" that protects the island.

[13][34] This plan was continued into season five, when Rousseau's husband, Robert, describes the monster as a security system that guards the island's Temple.

[25] The original appearance of The Man in Black as the monster was the first major plot twist of the sixth-season premiere, "LA X", which changed how the viewers and characters perceived the island.

[4][5] In the March 21, 2008, edition of the Official Lost Podcast, executive producer Damon Lindelof revealed that manifestations of the monster did indeed include Yemi and the medusa spider that bit Nikki and Paulo.

[36] In reference to Jacob and The Man in Black, Lindelof stated that, regarding the scene in "Pilot, Part 2" where Locke explains to Walt Lloyd the premise of backgammon using the concept of light and dark, he and fellow co-creator J. J. Abrams had planned for those two sides to eventually be personified by two individuals.