In a new "Inside the Episode" video released by HBO, showrunners David Benioff and D.B. Weiss discussed the final scene of last night's episode, "Oathkeeper." The scene revealed new information about the nature of the White Walkers and is the closest examination of how that race functions as a society that we've seen so far. "The White Walkers are obviously this threat that's looming over the whole world of the show," said Weiss, "whether or not anybody knows it. We know it, and we wanted to delve deeper into their world but we wanted to do it in sort of a specific way. Having grown up, as a kid, watching the old monster movies you realize the most effective mysterious, horrible things were the ones that remained mysterious, that the more you showed of something the less mysterious and horrible and the more mundane it started to seem. So we really wanted to take people very deep into their world, but in a way that preserved the fundamental mystery of that world." "Part of it was, it was something we were always curious about," says Benioff. "The very first time we saw Craster leave a baby, in season two, you're wondering, 'What the hell is that all about?' You see the White Walker take it. You don't know what's going to happen. Are the White Walkers going to eat the babies? Are they going to sacrifice them in some kind of ritual? We love the idea that there was one last baby that Craster had fathered before he died, and it's a moment that, while not in the books, is kind of suggested by the books and a moment that we thought would be really fun to illustrate in a kind of horrifying way. And it was actually pretty horrifying. It's the kind of thing that…the best effect is a real live baby that's actually unhappy because it's not with its mom." "The revelation of what the Walkers are actually doing with the babies we hope will come as a particularly nasty surprise to people," added Weiss. The final scene in "Oathkeeper" is one of the most significant in Game of Thrones so far, from a storytelling and adaptation perspective. While Game of Thrones has created scenes that are not seen in the A Song of Ice and Fire series before, they are usually connective tissue that illuminates the motivations of characters that don't have their own point-of-view chapters in the books or give characters a chance to say things that would be conveyed with interior monologue in prose form. The end of "Oathkeeper" is the first time we've seen Game of Thrones allow fans to delve deeper into the mythology of George R.R. Martin's world than even the books themselves, even if the scene brings up as many questions as it answers. The video also has Weiss and Benioff discusses Tyrion and Jaime Lannister's relationship and the loaded conversation between Littlefinger and Sansa Stark during their sea voyage to the Vale. You can watch the whole video, embedded below. Game of Thrones airs Sunday nights at 9 PM ET on HBO.