The characters on Lost had many secrets they kept from each other. In addition to the many unshared details of their respective backstories, new information was often slow to spread among characters because it was initially restricted to a small group.
This fact is often referenced in the show itself, as characters complained about not belonging to the "in" group at various times.
Some secrets listed below were eventually revealed over the course of Lost, while others have yet to be widely known. This page serves to keep track of all noteworthy unshared (or formerly unshared) character details, in order to keep tabs on who knows what.
Summary:Charlie became addicted to heroin through the influence of his brother Liam. When his stash began to dwindle after a week on the Island, he came clean with the help of Locke, though he had several near-relapses. ("Pilot, Part 2") ("The Moth")
Charlie told his brother Liam that "you did this to me", blaming Liam for his addiction. ("The Moth")
Jack revealed that he knew Charlie was going through withdrawal when they were trapped in a cave-in. ("The Moth")
Claire found out after talking to Eko about the contents of the Virgin Mary statues. She consequently banned Charlie from her tent and seeing Aaron, thinking he was using again. ("The 23rd Psalm")
Hurley found out in front of the camp fire while revealing his own secret of being a millionaire. ("Numbers")
Kate is a fugitive and murderer
Kate was a fugitive and murderer
Summary:Kate killed Wayne, who she originally thought was her step-father, after she found out that he was her biological father in 2001. She was on the run from the law ever since. ("Pilot, Part 2") ("Tabula Rasa") ("What Kate Did")
Locke wheeled up to Rose in the airport to pick up the medication she had dropped. Later, when he told her that it would take four weeks for him to recover from the blast door crushing his legs, she replied, "You and I both know it's not going take that long." ("S.O.S.")
Mikhail told Locke that "the John Locke I used to know was para-", but was interrupted by Rousseau. ("Par Avion")
Ben asked Locke about his sudden recovery from paralysis, and further revealed that he knew that Locke was paralyzed by his father knocking him out of a window. ("The Man from Tallahassee")
When Boone tires of lying to Shannon about what he and Locke are really doing in the jungle, Locke knocks Boone out, ties him up and drugs him. Boone has a vision in which Shannon dies which leads him to "let go" of his dependency on her and he keeps the secret. ("Hearts and Minds")
After failing to open the Hatch with a trebuchet, Locke has a vision of the Beechcraft and enlists Boone to find it, believing this will lead to a method to open the Hatch. Boone is critically injuried while in the airplane which Locke keeps a secret from Jack and the Losties. ("Deus Ex Machina")
Jin's father is alive
Jin's father is alive
Summary: Jin told Sun and Mr. Paik that his father was no longer alive. This was revealed to be a lie, caused by Jin's shame over his background. ("...In Translation")
Sun discovered the truth after Jin's biological mother blackmailed Sun to keep her profession a secret. Sun found Jin's father and agreed to keep his secret after talking to him in person. ("D.O.C.")
Sun knows English
Sun knows English
Summary: In Sun's first days on the Island, no one—not even Jin—knew that she spoke English. However, everyone learned of her secret after a month on the island. Sun learned English from Jae Lee after having an affair with him prior to boarding Flight 815, as part of her plan to leave Jin. ("House of the Rising Sun") ("The Whole Truth")
Who knows: Everyone
Sun revealed her secret first to Michael, to explain that Jin assaulted him for being in possession of Jin's watch. ("House of the Rising Sun")
Kate discovered Sun's secret based on her slight chuckle to Kate's joke while they were gardening. ("Hearts and Minds")
All of the survivors, including Jin, finally learned about her ability to speak English when she had to reveal it to defend Jin against accusations that he burned the first raft, since he could not comprehensibly defend himself. ("...In Translation")
He told Charlie his net worth, but Charlie did not believe him, saying, "I bare my soul, and all I get is bloody jokes." ("Numbers")
On the raft, Sawyer read the message Hurley wrote for the Bottle, but didn't recognize Hurley's real name. (He said, "Who the hell is Hugo and how's he got 160 million dollars to leave to his mom?")("Exodus, Part 2")
Hurley told Jack, and followed it with "I'm not crazy." Jack responded, "I'm not saying you are." ("Man of Science, Man of Faith")
Hurley told Libby and she believed him, he clarified this by asking her, "You believe me?" Libby replied, "Who would lie about that?" (This was a deleted scene).
After the raft burned, everyone suspected Jin, however, Locke confronted Walt and his response was that he had been moving his whole life, and he didn't want to move anymore, he liked the island. ("...In Translation")
Locke assured Walt that he did not suspect him of poisoning his father, just because he knew about the first raft. ("Born to Run")
After Michael was poisoned, Walt confessed to his father that it was he who burned down the first raft. Michael told him they could stay if he wanted, but Walt declared that they "have to go". ("Born to Run")
Kate referred to him by his real name in front of the whole group ("One of Us")
Sun poisoned Michael
Sun poisoned Michael
Summary:Michael got sick and Jack determined that someone poisoned his water bottle. Although Kate and Sawyer were early suspects, Sun was the one who did it, but it was Kate's idea. ("Born to Run")
Jack confronted Sun, who confessed she didn't want Jin to leave, and "only used enough to make him sick." Michael inadvertently drank from Jin's water. Jack agreed to not tell anyone. ("Born to Run")
She told the story about how she was shot to Sayid, but did not tell the ending when he asked what happened to the man. Sayid may have guessed her secret from her demeanor, because he said, "What good would it be to kill you, if we're both already dead?" when she handed him the gun and dared him to shoot her. ("Collision")
Eko's dark past
Eko's dark past
Summary:Mr. Eko used to be a feared drug dealer who was known for murders and threats in his homeland of Nigeria. Later he disguised himself, and lived as a priest. ("The 23rd Psalm")
Who knows: No one, but probing questions were asked in response to some of his unorthodox actions.
Charlie asked, "What kind of priest are you, anyway?" ("The 23rd Psalm")
Charlie attacked Sun
Charlie attacked Sun
Summary: As part of Sawyer's plan, Charlie attacked Sun, making it look like the Others were becoming more aggressive. Charlie participated in the plan to make Locke look like a fool. ("The Long Con")
Charlie and Sawyer discussed the plan in the forest after it was accomplished. Sawyer promised never to reveal that Charlie was involved. ("The Long Con")
Charlie confessed and apologized to Sun. Sun told Sawyer that she wouldn't tell Jin. It is unknown if she or Charlie revealed it to anyone else. ("Exposé")
Jin was infertile
Jin is infertile
Summary:Sun and Jin were tested for infertility. The doctor confided privately to Sun that her husband was infertile. ("The Whole Truth")
When Juliet found out that Sun was pregnant, Sun confessed that she had an affair and that Jin was infertile. Juliet included this bit of information on the recording she left for Ben. ("D.O.C.")
Hurley said, "Do I know you from somewhere?" to Libby, but he couldn't remember from where. ("Fire + Water")
Libby tried to misdirect him, by making up a story about his having stepped on her foot when he came on the plane. However, Hurley was the last person to board the plane, and Libby was already seated in the back section, so this was a lie. ("Dave")
Who knows: No one, not even Ana Lucia understands the significance of her employer.
Christian hired Ana Lucia to accompany him on a trip to Australia.("Two for the Road")
Ana Lucia and Jack never drew their connection before Ana Lucia's death. It is possible that Ana Lucia did know, since she asked if his father was a drinker, but she chose not to tell Jack.
Ben told Juliet that Michael could be manipulated in a way that would help them capture Jack, unaware that Paulo was eavesdropping. ("Exposé")
Michael apparently told Walt while escaping the island because he "had to tell someone". This caused Walt to become afraid of Michael, and start living with his grandmother in Manhattan. ("Meet Kevin Johnson")
After Locke showed Desmond the print-out from the Pearl computer, Desmond realized the correlation between the dates and the System Failure, concluding to Locke, "I think I crashed your plane." ("Live Together, Die Alone, Part 2")
Due to Pryce, it also seems that at least the majority of Others knew of this.
Alex finally found out when Ben was captured in front of Rousseau, with Rousseau just blankly staring at her. Ben finally told her the truth. ("Through the Looking Glass, Part 1")
Christian Shephard is Claire's father
Christian Shephard is Claire's father
Summary: Christian had an affair with Carole Littleton, who gave birth to Claire nine months later. Therefore, Claire and Jack are half-brother/sister. ("Par Avion")
Claire didn't make the connection that Jack was her brother yet, since Christian never told her the name of his son. In addition, Christian never told Claire his own name. ("Par Avion")
Once Jack made it off of the Island, Carole Littleton told Jack at Christian Shephard's funeral that Claire was on Oceanic Flight 815, believing that she did not survive the crash. ("There's No Place Like Home, Part 1")
Naomi was found
Naomi was found in the jungle
Summary:Naomi the parachutist crash landed on the island, and was found by Desmond, Charlie, Hurley and Jin. She was treated by Mikhail and brough back to camp, but they didn't tell Jack because they didn't trust him anymore. ("Catch-22")("D.O.C.")("The Brig")
Summary: After being led to the Black Rock by Locke in order to kill Ben Sawyer discovered Anthony Cooper and in a fit of rage strangled him to death which Locke thanked him for.("The Brig")
Richard met him as a child when he was still a member of DHARMA. He also helps Ben destroy them.
Ben tells Locke that he is right that he is a compulsive liar, and starts off by telling him that he was a member of DHARMA and killed them all. Once he tells him this though, he shoots Locke, and Ben assumes he left him to die in the pit.
Charlie comes into contact with Penny in the Looking Glass and finds out that she is not a member of her search party. He manages to tell Desmond this before he drowns.
Ben tells Jack that Naomi is not who she says she is and is one of the "bad guys". He tells Jack if he contacts her boat, they will all die because of her.
Locke kills her without any explanation or compromising anything with her, which implies he somehow knew that she was bad for the island. Locke may have killed her because of his obsession with staying on the island, (the reason he blew up the submarine). He may believe, just as many of the survivors do, that the boat that is there and can take them away from the island.
When Desmond arrives back from the Looking Glass, he passes on the message to everyone at the beach and they radio Jack with the news.
Penny helps the 6 cover their tracks by transporting them to Indonesia.
It was Locke's original idea for them to lie, and when he gets off of the Island in the future, he would certainly know this.
Lapidus and Desmond escape the Island with the Oceanic 6, but do not arrive in Indonesia with them in order to cover the conspiracy.
Walt personally came to ask Hurley why they were lying.
Sun tells Widmore that he already knows they are lying.
Kate tells Cassidy that the Oceanic 6 are lying to explain how she knows about Clementine and Sawyer, and how Sawyer is still alive. Cassidy also knows Aaron is not really Kate's baby.
Hurley tells Carmen that the Oceanic 6 lied and the general outline of what happened on the island. ("The Lie")
Kate tells Carole they are lying before she goes back to the island so Carole will know Aaron is her grandson, hoping she will take care of him until Kate comes back. Carole also knows Claire is still alive and that she left the rest of the survivors and Aaron. Kate promises to bring Claire back to Carole.
Hurley saw Jacob's cabin
Hurley saw Jacob's cabin
Summary: Hurley indicates to Locke that the cabin he is looking for is in the other direction, but when asked for some specifications, he pretends he was referring to the plane's cabin. ("Confirmed Dead")
Who knows: Hurley, Locke and Ben. Also Sawyer, Claire, and Miles, although they don't know what the cabin and Jacob are.
Locke and Ben both gave him surprised looks when he mentioned the cabin. After the attack on the Barracks, they ask him to help them find the cabin.
Michael is Ben's spy on the freighter
Michael is Ben's spy on the freighter
Summary: Ben sent Tom to Manhattan to recruit Michael after his departure from the Island. After he agreed, they provided him with a fake name (Kevin Johnson), a fake passport, and a job as a deck hand on the Kahana, the freighter owned by Charles Widmore. Ben is doing this in an MEHP effort to stop Widmore from finding the Island. ("Meet Kevin Johnson")
Summary: As Daniel, Charlotte, Sun and Jin make their way to The Staff, Jin notices that Charlotte seems to react emotionally when he speaks to Sun in Korean about the future of their child. He later confronts her that night, and after he threatens to hurt Daniel, Charlotte begins speaking to Jin in Korean. ("Something Nice Back Home")
Jin found out after confronting Charlotte the night after they went to The Staff.
Later, on the way to The Orchid, Jin tried to tell the group something, and asked Charlotte to translate, reveiling to the people there that she spoke Jin's language. ("This Place Is Death")
Daniel's experiment caused Teresa to have Temporal Displacement
Daniel's experiment caused Teresa to have Temporal Displacement
Summary: While researching time travel as a professor at Oxford University, Daniel experimented on his then-girlfriend Teresa. However the experimented went terribly wrong, resulting in Teresa in a permanent coma-like state, her consciousness continuing to travel around in time.
Charles Widmore agreed to pay for her medical care after the experiment went wrong. ("Jughead")
After tracking down Daniel at Oxford University and finding out he was shamed, Desmond Hume visited Teresa under the care of her sister Abigail Spencer and learnt of her condition. ("This Place Is Death")
Miles is Psychic
Miles is Psychic
Summary: Miles has the ability to communicate with the dead.
Lara Chang found was the first to find out her son was psychic when he found a corpse in a neighbouring apartment, and claimed to hear it talking. He later came to her again to ask her the truth about his father and his powers. ("Some Like It Hoth")
Although is unclear how they both found out, Naomi Dorrit and Matthew Abaddon recruit him onto the freighter mission because of his powers, with Naomi calling Miles "a ghostbuster." ("Confirmed Dead")
Miles openly tells Hurley about his ability when he discovers the body of Alvarez in the back of the truck. Hurley tells him that he can also communicate with the dead, and sometimes plays chess with them. ("Some Like It Hoth")
Refused Ben's offer of the 3.2 million dollars after revealing to him that he knows about Nikki and Paolo and the diamonds. ("Dr. Linus") He also told Ben what Jacob was really thinking when Ben murdered him.
Senses the buried body of Alex Rousseau when trekking with Richard; the latter reveals he buried her after she was shot by Keamy. ("What They Died For")
