The Second part of the series finale rests firmly on the mystery of who these people are, how they define themselves and what they want to be remembered for. As touching as it is for Sawyer to define himself as a lawman, it's his heart what really defines him - as proudly hinted by Jin & Sun moments before he encounters "Doc" - he almost get it by the time he reaches the woman standing near a vending machine, moments fleeting by as they realize each one is the soulmate the other was looking for; Juliet, finally, asks James to go for a coffee and Sawyer is blissfully aware that, at last, he found her.
Oddly enough, no one can reach Jack for he's too far gone to go back; "you don't have a son" seems like a cruel joke rather than the wake-up call Locke intended, Sawyer in the hall only pushes him to go faster and no matter how much Kate has missed him since the last time they said "I love you" he can't snap out of it. The cut on his neck no longer a nuisance but rather the impending threat hanging over his head, for no matter how many times he kills the MIB or how many people he saves before the end, Jack refuses to let go. Yet we've all known it was supposed to be Hurley, we've known that since the beginning when he conspired with the Universe in the form of Desmond and Boone, Jack's death - as foretold since the season premiere with the scar on his side and the cut in his neck - the trigger that Desmond had been trying to control ever since "Happily Ever After", the clues scattered throughout the season finally collide in a magnificent symphony, as perfect as Daniel's concert, as old as time itself.
The island shatters along with these people's lives, Ben refusing to leave it as strongly as Jack refuses to move on; Frank lifts the Ajira off the ground same as Hurley lifts Desmond using all his might. Jack's agonizing steps echoes his father's behind him, for everybody dies, some before you and some long after it. Thus, Jack's successor says Goodbye to the best number two he's ever had, obvious by now how his & Ben's work was finally done; somewhere beyond the island the spirits of the people they intertwined with are waiting for the last one of them, a man who died alone, not long ago, in a field of bamboo ... the Doctor whose spirit is finally ready to let go by the time his eyes close for the very last time.