Game of Thrones showrunners still don't know how George RR Martin's books will end

The fantasy series moved ahead of Martin's books at the end of its fifth season, with Benioff and Weiss crafting the final three seasons in collaboration with the author.

But as Martin is still working on the final two books of the fantasy series, the two showrunners have reiterated that his books will diverge from the end of the TV series.

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"[The concern] used to be that the books would spoil the show for people — and luckily it did not, for the most part," Benioff told Entertainment Weekly. "Now that the show is ahead of the books, it seems the show could ruin the books for people. One thing we've talked to George about is that we're not going to tell people what the differences are, so when those books come out people can experience them fresh."

The author is currently working on the sixth book in his seven-part series, titled the Winds of Winter.

"George discovers a lot of stuff while he's writing," Benioff said. "I don't think that final book is written in stone yet — it's not written on paper yet. As George says, he's a gardener and he's waiting to see how those seeds blossom."

Martin himself meanwhile has said that he is surprised that the end of the TV series has come so soon.

“I don’t think it should be the final season. But here we are," he said recently. “Has it been longer than that? The time has passed by in a blur.”

Game of Thrones series 8 begins on 14th April on Sky Atlantic in the UK and HBO in the US