Back in September, "Game of Thrones" star Kristian Nairn (Hodor) gave fans -- and apparently, showrunners -- quite a surprise when he let it slip that both Hodor and Bran (Isaac Hempstead Wright) would be sitting out the entirety of season five.

HBO initially kept as mum as Hodor about the issue, but now they're letting showrunner David Benioff explain their surprising decision: Just as many suspected, it all has to do with Bran's storyline catching up with the source material, George R.R. Martin’s most recent "A Song of Ice and Fire" novel, "A Dance with Dragons."

“Ideally that wouldn’t have gotten out and it’s unfortunate it did,” Benioff told Entertainment Weekly. “The fact is, even though we’re making changes to the books and adapting as necessary, we’re trying to keep the various storylines the same as the books and trying to keep them roughly [chronologically] parallel. And last year we caught up to the end of Bran’s storyline. So if we pushed him forward this season, then he’s way ahead of where the other characters are.”

This makes perfect sense, as many viewers were alarmed to see Bran wrapping up plot lines from book five at the end of last year, while characters like Jon Snow (Kit Harrington) and Tyrion (Peter Dinklage) were firmly back in book three.

Also, as Benioff pointed out, the stuff coming up in Bran's storyline involves him hanging out in a cave and talking to a Raven. It's certainly not as compelling as Arya's (Maisie Williams) journey to Braavos, or any of the drama that will soon be going down in King's Landing.

“It made sense to stop where we did,” Benioff continued. “He’s now entering a training period which is going to take quite some time, much of which isn’t particularly cinematic. So rather than being stuck in a cave for a year, we figured it would be interesting to leave him out for a little bit, so when you see him again...”

... He's sprouted a second head and speaks fluent warg? Who knows what's coming up next for Bran, but let's not give up hope that Martin's upcoming book, "The Winds of Winter," will be available before "Thrones" begins shooting season six.