In a new interview for a Vanity Fair cover story, Game of Thrones co-creator David Benioff says that they met with George R.R. Martin to learn the ultimate ending for the series.

Benioff says they went to the author’s home in New Mexico last year to learn what Martin has in store for the final books so that they can point their television adaptation towards the conclusion.

“Last year we went out to Santa Fe for a week to sit down with him [Martin] and just talk through where things are going, because we don’t know if we are going to catch up and where exactly that would be,” Benioff says. “If you know the ending, then you can lay the groundwork for it. And so we want to know how everything ends. We want to be able to set things up. So we just sat down with him and literally went through every character.”

Martin noted that they don’t have specific details but do know the larger endgame. “I can give them the broad strokes of what I intend to write, but the details aren’t there yet,” he says. “I’m hopeful that I can not let them catch up with me.”

Elsewhere in the interview, Vanity Fair notes that Martin is aware the actors – particularly the young ones – are aging quickly while they’re not growing up as fast in his series. “This is a serious concern,” the author says. “Maisie [Williams] was the same age as Arya when it started, but now Maisie is a young woman and Arya is still 11. Time is passing very slowly in the books and very fast in real life.”

Benioff and his fellow co-creator D.B. Weiss added that they expect the show will run for “seven or eight seasons” in total, according to the magazine. Says Weiss, “It doesn’t just keep on going because it can. I think the desire to milk more out of it is what would eventually kill it, if we gave in to that.”

Read more over on Vanity Fair. Game of Thrones season 4 premieres Sunday, April 6 at 9 p.m. eastern/pacific on HBO.