Lost: season 6 episode 13 - The Last Recruit

Hurley, Sun, Lapidus and Jack join Locke's group. Locke says he was hoping they'd come. Jack and Locke walk away to talk privately. Jack is surprised this person looks so much like Locke, but it bothers him that he doesn't know who this person is. Jack asks why use John Locke, and Locke says because he was stupid enough to believe that he was brought to the island for a reason, and that belief got him killed. And because Jack was kind enough to bring his body back here. Jack realizes Locke had to be dead before this person could look like him, and then Jack asks who else has he looked like. Was he Jack's dead father? Locke smiles and says yes, that was him. Angry, Jack asks why. Locke says they needed to find water. It may be hard to believe, but all he ever wanted was to help Jack leave. But because Jacob chose him, Jack was trapped on the island before he ever got there. But Jacob is dead now, and they don't have to be trapped anymore. They can all get on the plane and leave whenever they want to. Jack asks if he can fly away whenever he wants, why is he still there? Locke says it has to be all of them.