DISCLAIMER: I don't own LOST or any of the characters.
Because the headland where they'd buried Boone so many months ago was over-crowded with graves, Sayid and Michael dug Kate's grave on another hill overlooking the sea. When he saw it, Jack wondered if they'd chosen that one so Kate would be as alone in death as her life had once been.
He'd planned on digging the grave himself, he'd thought maybe it could detach him from the thought of her body. But then Jack couldn't let go of Kate (of course he couldn't) and so Sayid and Michael did it without mentioning it, without asking for permission or approval or even acceptance of their plans. Or maybe they did; there were long hours when Jack knew nothing but Kate's body cooling in his arms.
He can't deny the others their right to a funeral for Kate, though he wants nothing more than to bury her himself, alone, to have his last moments with her in peace.
But who could he fool with that? Kate died hours ago. And he had his last moments with her, because when he knew that this was it, he'd screamed at Sun and Sayid and Locke, sent them scurrying out of the tent and gathered Kate up, feeling her too-hot breath rasping against his cheek (like when they made love) and clutching her hand and trying to will her to be alive, trying to will Locke's island into giving him a miracle.
So Sun and Michael gently prise him away from Kate's body, and though he remembers the way it felt against his it's not the same anymore and he's empty as Sun tries to give him herbal tea and Sayid and Michael are loading Kate's body onto a stretcher. He insists on carrying it with them, and his voice is thick and no one argues. He covers Kate's body with a blanket, as though she was still alive and just sleeping, but this time he drapes it over her face and sterile blue separates Kate from the world. They are a silent procession up to the hilltop grave: Jack and Sayid, Claire and Sun as unlikely pallbearers and everyone else trailing along behind them. It was this way when they buried Boone, when they buried Tracey, when they buried Shannon, when they buried David, but this time Jack can't help feeling that it is the end of everything he's ever known.
She shouldn't be dead, Jack thinks, and stands beside her grave listening to heartfelt sentences which seem only platitudes in the face of his drowning grief. Shouldn't be dead. Appendicitis, of all things, appendicitis that wouldn't have killed her in the real world and shouldn't have killed her here. Sun keeps saying that it's not his fault; she's being saying that ever since it became clear that the operation, in which Jack had wielded one of Locke's knives and cut open the smooth white stomach of the woman he loved, had left her with an infection that became a ravaging, rampaging force that took over her body. Jack had heard Sayid and Locke murmuring outside the tent where Kate lay dying - talking about whether they should kill her, a word that once had no place or acceptance in Jack's lexicon. He'd tried to find the words to say that he hated this long slow painful death, hated it as a doctor and as a lover, but that he didn't have the strength to end her pain. They'd have done it, if he asked them, but for once he couldn't be heroic or noble, and he held her and kissed her damp forehead, whispering into her ear until she lay dead in his arms.
They all say it's not Jack's fault that Kate is lying in this hole above the ocean and they're piling dirt in on top of her. It's not Jack's fault, because he loved Kate and if he couldn't save her then there was truly no saving to be had. But he can't believe that, he wants to believe that this time love should have done it, that this time there should have been a miracle.
Locke marshalls the rest of the survivors. Michael has his arm around Walt, Sun clutches Jin's hand, Claire is crying, clinging desperately to Charlie and Aaron. Hurley walks apart from the rest, looking at the ground; Sayid's head is up and his eyes cool, as they've been ever since the day Shannon's beaten body was brought ashore by the tide before anyone really knew she was missing (and maybe it would have been easier if the Others had killed Kate like they'd killed Tracey and Shannon and David).
Even Sawyer has found tears, and maybe he's the only one who has any idea of the depth of the loss of Kate.
Jack watches them all go, back down the path to the camp, back to the strange reality of life on this island, in this situation, and then he sinks to his knees beside the fresh dirt of the grave. He sits there and stares out to sea and searches for so many ways this could have worked out differently.
Years later, when they've been on the island for twelve years and Kate has been buried for five, they are suddenly, unexpectedly, rescued and returned sharply to the real world. When he steps aboard the boat that takes them away from home, Jack has in his pocket a handful of dirt from Kate's grave and a small toy plane.
He takes nothing else from the island.
THE END