If you watched the Game of Throne’s season seven premiere (and I have to imagine you did if you're bothering to read this article), then you'll probably remember Sandor Clegane, AKA The Hound staring into a fire and envisioning a wall of ice. Specifically The Wall.
Kind of a sad moment because the scene follows the demise of the family he'd left to starve in season six, but the emotional heft of the situation no doubt led the Lord of Light to give The Hound insight that could change everything...