When HBO decided to make a TV series of George R.R. Martin's A Song of Ice and Fire books, creators D.B. Weiss and David Benioff sat down with Martin and he told them how the story ends, in broad strokes. But now that the show is catching up to Martin's books, he's told them in much greater detail, character by character.
In the new Game of Thrones feature in Vanity Fair, Martin confesses that the show is catching up to his writing speed, something he had sworn wouldn't happen. Says Martin, "They are. Yes. It's alarming." (Already, our panel of experts has speculated that season five, airing next year, could end with events from The Winds of Winter, the book Martin hasn't finished yet. Warning: link contains spoilers.)