Timey-wimey stuff. So complicated, sometimes, and other times so simple.
Amy and Rory aren't dead. Not really. Oh, they're dead now, in 2012. But at the moment after they're whisked away by the Weeping Angel, they are living in 1962, New York.
For most of the following forty-plus years, they live very comfortably. Amy writes science fiction novels. Amelia Williams is a generic enough name that she doesn't think she'll catch her own attention. But she might catch the Doctor's. She knows she'll catch her daughter's, because River sends her the Melody Malone novel. She publishes it under another pen name, along with a series of books about Melody Malone.
Each book she writes, except of course the original Melody Malone mystery, starts with a forward. She insists upon it and makes sure it's in each book's contract, so that if it's ever re-printed, the forward will be too.
"Spoilers!" one begins. "Doctor and Companions: Do not read until after you have visited the town of Mercy in the Old West."
Each novel starts that way, referencing a different adventure, just in case she or her Raggedy Man do come across any of these books. Amy knows the perils of knowing your own future.
The Time Traveler Chronicles never gain great popularity, but that's OK, because she and Rory make a more than comfortable living for themselves by investing heavily in Lava Lamps. Yes, Lava Lamps.
By chance (Amy often wonders if there is such a thing as chance), they read a slightly mocking business feature about a man trying to market psychedelic lamps in the United States. At this point it is 1965. Rory has been working as a nurse, and she's been a history tutor and freelance writer for a few magazines. They're not making much money, but they take every penny they have saved and buy as much stock as they can in the Lava Manufacturing Corporation, to the dismay of their friends.
By 1969, they're rolling in money, much of which they reinvest in stock in a company that's making disco balls. A decade later they invest, with an eye for the long term, in IBM, with the result that by the time they're retired, they're living very comfortably indeed. As are the three children they've adopted. They feel slightly guilty for about five minutes about this "insider trading," but that abates when they remind each other how often they've saved the world.
But that's getting ahead of things. Back in 1962, they agree they should stay in America. What if they ran into their parents? Or, eventually, their future selves? Or the Doctor? They've noticed he spends way more time in England than any other country. And then there's the fact they have to one day be buried in New York in order to avoid creating a paradox that would collapse the city. No pressure.
But most of all they decide to stay in New York because they want to start over. Their lives have changed, in an instant. Everyone and everything they ever knew has been taken from them. Their friends, their jobs, their family, their house. Their lives as time travelers. Their daughter. The Doctor. All ripped from them without a moment to say goodbye.
In that minute between when he disappears and when Amy appears before him, Rory doesn't have time to panic. He knows she'll come for him, to save him. But when she does appear, tears streaming down her face, he knows it won't ever be the same. This time, there's no going back.