We now know who the six are but why?
JackShephard - Sick
Sun-HwaKwon - Pregnant
Hugo "Hurley" Reyes- ????
The Oceanic 6 were described as international celebrities. Hurley tried to use this status to get gentler treatment from the police when he was arrested for reckless driving. ("The Beginning of the End") Evidently, the six also became frequent targets of media investigations, such that Sayid initially thought Ben was a reporter when he caught him taking photos of Nadia's funeral procession in Tikrit. ("The Shape of Things to Come")
The members received golden passes for unlimited free travel from Oceanic Airlines. ("Through the Looking Glass") Sayid claimed to have received a large cash settlement from Oceanic. ("The Economist") Kate's standard of living during her trial, with a house in the Hollywood Hills, also suggested a substantial settlement. ("Eggtown")
There are interpersonal tensions among the Oceanic 6. Jack initially won't visit Kate at her home, not wanting to see Aaron. ("Eggtown") He eventually relents, and they become engaged, but after he begins to abuse medication and she performs a chore that Sawyer apparently asked her to do before she left the island, their relationship deteriorates. ("Something Nice Back Home"), ("Through the Looking Glass").
After the birth of Sun and Jin's baby Ji Yeon, Hurley is the only one to visit her; the two are friendly, but Hurley is relieved to be the only one there. ("Ji Yeon") Sayid's work as an assassin is said to be to protect his "friends", but it is unknown who he is referring to. ("The Economist") .
For a time following their rescue, the members of the Oceanic 6 kept the actual story of what happened following the crash a secret. In public, they adhered to a fabricated story about their time on the Island.
According to this story, Oceanic Flight 815 crashed into the Pacific Ocean, and only eight people survived the impact. The Marshal died in the crash, and Jack never spoke to him. Jack was injured, and Kate dragged the survivors out of the water and onto a nearby deserted island. Kate administered first aid to some of the survivors and found food for them. At some point two of the original eight survivors died. Jack maintained this story under oath at Kate's trial, ("Eggtown") and Hurley maintained it while under police questioning, ("The Beginning of the End") telling officer Mike Walton that he never met Ana Lucia. A grave marker for Jin in South Korea listed the date of the crash as his date of death. ("Ji Yeon").
After Hurley was re-admitted to Santa Rosa Mental Health Institute, Jack visited him and questioned him to make sure his apparently deteriorated mental health status wouldn't diminish his adherence to the story. ("The Beginning of the End") Matthew Abaddon suspected the story to be false, and questioned Hurley about it. ("The Beginning of the End")
After several years of maintaining the story, however, Jack told Kate that he was "sick of lying". ("Through the Looking Glass")
What we don't know:
What secrets are the Oceanic 6 keeping, and why?
When and how will the Oceanic 6 leave the Island?
How is their survival reconciled by the public with the prior discovery of Oceanic 815 with no survivors?
Who are the other two people who (according to the official story) survived the crash but died on the island?