<P> When Naomi Dorrit (Marsha Thomason) addresses the camp about the world's perspective of their predicament, Claire expresses outrage they are considered dead . Later, when Karl (Blake Bashoff) arrives the next day with news of the Others' impending arrival, Claire goes with the rest of the camp to the radio tower . Soon after, Claire is delighted to hear Charlie has disabled the jamming device blocking all outgoing signals, but is worried he has not returned to shore . </P> <P> Claire and Sun tend to Aaron before heading back to the beach, following Jack's success in contacting the freighter . However, upon the two groups meeting by the cockpit, Claire learns of Charlie's death and his final warning . With this in mind, Claire decides to join Locke and move into the barracks, along with Hurley, Sawyer and three other unarmed castaways . Along the way, she and the rest of Locke's group encounter Charlotte Lewis (Rebecca Mader), who had parachuted onto the island . Claire is asleep when the barracks fall under attack . One of Martin Keamy's (Kevin Durand) men shoots an RPG at Claire's house, which explodes, but she is rescued by Sawyer . Upon safely leaving the barracks and its attackers, Claire, Sawyer and Miles Straume (Ken Leung) return to the beach . Several times during the journey, Miles stares at Claire strangely, prompting Sawyer to issue an impromptu' restraining order' . She falls asleep in their camp that night and wakes to find her father, Christian, holding Aaron, and proceeds to follow him, leaving Aaron under a tree in the process . Later, when Locke enters Jacob's cabin, he finds Claire sitting there with Christian, claiming she and Aaron are fine where they are . Before Locke leaves, Christian cautions him Claire's whereabouts should remain a secret . </P> <P> Aaron is one of the rescued Oceanic Six, and the general public are told he is Kate's son, while Claire is listed as among the passengers who did not survive the plane crash . At Christian Shephard's memorial service, Carole Littleton, who has recovered from her coma, tells Jack she and Christian had a relationship which produced Claire, revealing her to be Jack's half - sister . Eventually, before departing to return to the island, Kate reveals to Carole that Aaron is Claire's son . Kate tells Carole that she is going back to try to find Claire, and leaves Aaron with his grandmother . </P> <P> On the Island, Dogen (Hiroyuki Sanada) tells Jack that Claire has been consumed by the same "infection" that threatens Sayid . At about the same time, Jin is attacked by men from the temple, and then rescued by Claire, who has adapted to an existence on the Island like Rousseau's . She tells Jin about a friend she now has on the island, the fake John Locke--of whose falsity she is aware . Claire reveals that she's been searching for Aaron and believes the people in the Temple have him . Observing Claire's erratic behavior, Jin decides not to convince her otherwise . She therefore plans to invade the temple to find her son . </P>

When do we find out claire is jack's sister