John Locke was one of the middle section survivors of Oceanic Flight 815. Before the crash his father conned him for one of his kidneys and later pushed him out of a window, breaking his back, causing him to have to be in wheelchair. After this he spent the next four years of his life paralyzed from the waist down and looking for his purpose in life. He was then told by Matthew Abaddon that he must attend an Australian Walkabout after which he found himself aboard Flight 815. His paralysis was immediately healed upon crashing on the Island, which ultimately led him to believe that he had some sort of special connection to the Island. John was very handy with tools and a good hunter of boar and other animals of the Island, which proved to be very helpful in the survival of the group. Seen as antithetical to Jack Shephard, he and Jack were philosophical opposites and used to share leadership among the survivors.
When Locke discovered a Hatch on the Island, he was determined to open it, insisting that everything happened for a reason. He opened it and took it upon himself to continue pushing the button, believing that this was his purpose. However, Locke soon lost his faith in the Island and stopped pushing the button which ultimately caused the discharge. After this, Locke looked for his purpose again and led the mission to rescue Jack from the Others. Locke eventually decided to stay with the Others and with Sawyer’s help, he passed the test of killing his father. However, his apparent ability to commune with Jacob made John a threat to Ben, who shot him and left him for dead in the DHARMA Grave.
An apparition of Walt (possibly the Man in Black or the Island itself) found Locke and told him that he still had work to do. (This phrase was previously spoken by the MiB as Christian, hinting that he was impersonating Walt.) After Jack called the freighter for rescue, John (convinced that the freighter had no intention of helping them) led a group of his supporters to the Barracks for safety, where they were attacked by mercenaries. After the Oceanic Six left and Ben moved the Island, John assumed leadership of the Others, but was immediately separated from them as a result of the Island skipping through time. Locke left the Island via the Orchid, in an attempt to stop the erratic flashes through time and bring back everyone who left. After trying and failing to reunite them, John attempted to take his own life, only to be stopped and then strangled by Ben. His death was used to convince the others to return to the Island. John’s corpse was placed upon Ajira 316 and crashed on Hydra Island along with the plane in 2007.
After the crash, Locke appeared to have been resurrected, rejoining the Others and embarking on a mission to assassinate Jacob. However, his body was discovered in the hold of Flight 316 some days later. John Locke had been dead all along and had been replaced by The Man in Black. After several days he was finally buried in the graveyard. Jack later carried on and fulfilled Locke’s goal of protecting the Island.
2×01 – Man of Science, Man of Faith
Upon entering the newly opened hatch (discovered to be the the Swan Station of the DHARMA Initiative), Locke was briefly held captive by Desmond, the operator of the station. (“Man of Science, Man of Faith”)
2×02 – Adrift
Locke headed down into the Hatch after Kate went missing inside. He found her dazed on the floor and Desmond suddenly appeared behind him holding a gun, and asked him “Are you him?”. Locke pretended that he was indeed “him”, but Desmond realized Locke was lying. Locke then tied Kate up and secretly placed a pocket knife in her trousers.
After this he explained the plane crash to Desmond and heard the countdown timer for the first time. Desmond then ordered Locke to input the numbers into the computer. (“Adrift”)
2×03 – Orientation
Desmond showed Locke & Jack the Swan Orientation Film and fled after he accidentally shot the Swan Computer. Locke continued his job of entering the Numbers and pushing the button, which he believed was extremely important. (“Orientation”)
2×04 – Everybody Hates Hugo
He believed the button was so important he helped establish a rotation of the castaways for pushing the button, so it could be done efficiently. (“Everybody Hates Hugo”)
2×06 – Abandoned
Later on, he discovered that Charlie had been hoarding heroin-filled statues from the Beechcraft, upsetting him because he considered it a breach of trust. (“Abandoned”)
2×12 – Fire + Water
Shortly after, he severely beat Charlie following Charlie’s kidnapping of Aaron, instigated by a series of delusions and subsequently became quite close to Claire in a fatherly manner (and made Charlie jealous of his good relationship with Claire). (“Fire + Water”)
3×14 – Exposé
On day 49 following the crash, Locke was passing Paulo on the beach as Paulo appeared to be burying something (the diamonds). He provided some more words of wisdom about the island, stating that “things never stay buried”, and offering some advice on where to bury whatever he was burying further inland or up the beach, due to beach erosion. (“Exposé”)
2×14 – One of Them
Due in part to the subtle manipulations of Ben Linus, who had been captured by the castaways while masquerading as “Henry Gale”, Locke found himself at odds with Jack for “leadership” of the group and the role of decision-maker. (“One of Them”)
2×17 – Lockdown
He initially believed Ben’s assertion that he was not one of the Others and called on Ben’s help when his leg was impaled by a blast door during an impromptu lockdown in the Hatch. He consequently promised to protect Ben from the other survivors.
While he was impaled he discovered a hidden map drawn of the Island on the blast door. (“Lockdown”)
2×19 – S.O.S.
Following the revelation of Ben’s deception, Locke was thrown into a state of self-doubt when Ben claimed that he never pushed the button and that nothing happened.
His faith in the Island’s abilities was bolstered a bit with a conversation with Rose, who made it clear that she was also aware of the Island’s healing properties. (“S.O.S.”)
2×21 – ?
Shortly after Ben’s escape from the Swan, Eko had a dream in which Ana Lucia and his brother Yemi told him to help Locke and to go to the “question mark”. Eko asked Locke to help him find the escaped prisoner, but later in the jungle he told Locke that they are really in search of the “question mark.” Locke refused to tell Eko what the question mark is, so Eko knocked him out with a headbutt. When Locke awoke, he showed Eko his sketch of the blast door map, and Eko decided that they must find the question mark as shown on the map. Then, they arrived at the Beechcraft in which Boone died. Locke mocked his past ideas and implied that he still blames himself for Boone’s death.
That night Locke had a dream involving Yemi and Eko climbing the nearby cliff. He told Eko about it, and Eko climbed the cliff. When he got to the top he saw a question mark in the salted ground below. Originally, it was a circle but some of the grass had grown back and now resembled a question mark. Realizing that this was a sign indicating that the plane was on the spot where something was hidden, the two men dug under the plane and found another hatch.
The new hatch was another DHARMA station called the Pearl, containing a film which suggested that the act of pushing the button was nothing more than a psychological experiment. This information (along with Ben’s false claim that he didn’t push the button and nothing happened) shattered Locke’s faith in the Island, while due to Eko’s dream, Eko took away the opposite belief – that pushing the button was essential. (“?”)
2×22 – Three Minutes
Later that day, Locke witnessed Charlie hurling the remaining heroin statues into the ocean. He also finally ripped off the splint supporting his leg, having fully recovered from his injury in the Swan station. (“Three Minutes”)
Locke tries to convince Eko to let the timer run down and tries to destroy the computer with the Jesus stick, but Eko stops him. They fight, and Eko locks him out of the the Hatch.
Charlie discovers Locke weeping in the jungle, and informs him of Desmond’s return. (“Live Together, Die Alone, Part 1”)
Locke became determined to prove that the button was meaningless. He entered into a partnership with the returned Desmond who triggered a lockdown that shut Eko out of the Hatch, intending to wait until the countdown ended on the assumption that nothing would happen. While waiting for the timer to run out, Desmond read printouts from the Pearl and realized that the whole thing was legitimate due to a systems failure he remembered causing two months ago. When he then attempted to push the button, Locke smashed the computer in protest.
As the countdown ended and the electromagnetic energy beneath the station began to build up, Locke spoke only three words—”I was wrong”—to Eko, who had made his way into the computer room. (“Live Together, Die Alone, Part 2”)