"What do you see?"
He sees nothing, at least for a second. Then it comes. A vision. An essential vision. "A wall of ice," he says, the reflections in his flickering eyes our only glimpse into R'hllor's tease. "The Wall." Oh, we're familiar! "Where the wall meets the sea." Go on... "There's a castle there. There's a mountain. An arrowhead. They're marching past. Thousands of them."
Now that sounds like a trouble.
For all the politicking from the last six seasons of Thrones, "Dragonstone" is the first episode that plainly states the show's end game. Forget the wages of war against man and man -- that's a game for shortsighted, power-hungry dynasty-chasers like Cersei. This war, The Big One, is with the White Walkers, and Sandor is the first person to witness just how bad it's going to be for people. Because The Wall isn't going to stop The Night's King this time. As Sandor details, the leader of the undead is marching towards Eastwatch-by-the-Sea, a fortress positioned along The Wall and the Bay of Seals. But didn't the Walkers stop short of entering the water and attacking Jon Snow during the Battle of Hardhome? Apparently they're not as hydrophobic as we thought.
Does the Lord of Light show Sandor these visions to aid their quest or spell an inevitable armageddon for all of mankind? What does he really see? The secrets may lie in Beric's position in this mess.
"Poor Beric Dondarrion, who was set up as the foreshadowing of all this," author George R.R. Martin told Time in a lengthy and revealing Season 7 interview. "Every time he’s a little less Beric. His memories are fading, he’s got all these scars, he’s becoming more and more physically hideous, because he’s not a living human being anymore. His heart isn’t beating, his blood isn’t flowing in his veins, he’s a wight, but a wight animated by fire instead of by ice, now we’re getting back to the whole fire and ice thing.
Martin positions Beric, more man than we'd ever consider The Night King, to be the fiery inverse of your average White Walker (which explains his abilities to conjure a fire sword, as seen in the trailers for Season 7). Perhaps Sandor, embracing the fire half of this dual god, is the only force that can wallop the White Walkers in hand to hand combat? Not only will the Brotherhood without Banners travel to Eastwatch-by-the-Sea to face their fate, they'll now do so in the context of a religious war, where the forces summoned by light and dark, fire and ice, square off. Melisandre's quote from Season 4 only makes the god's involvement in the showdown all the more ominous: "There's only one hell," she tells Shireen Baratheon, not yet burnt at the stake in honor of this Lord. "The one we live in now."