Winter in the Underground often lasted a few months. Dusk descended earlier and dawn was late to come. Sometimes snow appeared, other times it didn't.
The year after The Run, the Underground was struck with a blizzard which covered the Labyrinth higher than its walls and froze the Bog of Eternal Stench. The denizens of the Underground who were unfortunate enough to be out and about froze into icicles. When touched, they disintegrated into pure white snow.
Winter soon became something to be feared after that. Each year, the frost grew more and more. Darkness covered much of the Underground as the daylight waned.
It began in increments. Whispers and rumors of dark places in the labyrinth. Places where goblins entered and never came back. Some scoffed that it was naught but another oubliette. But more and more denizens disappeared.
His subjects began to approach the King in earnest. Droves of Underground residents trekked to the center of the Labyrinth. But the King was not in attendance.
Complaints and murmuring could be heard day and night in the palace and still the King did not appear. The darkness crept over the land; leaving the rest of the Underground in perpetual dusk.
Year after year, the Underground suffered. Until at long last only the palace remained. The Undergound folk had ceased seeking sanctuary at the palace for they found out that it wasn't the safest place to be; darkness lurked in its crevices. Phantom voices could be heard softly whispering, often heralded by a chill in the air. Those that did not leap away from these places simply vanished from existence mid-breath.
On the first day of the thirteenth year of winter, the Underground ceased to be. It began with slowly falling snow which covered everything in sight. The denizens of the Underground looked up into the sky and whispered prayers to their King. They wondered where He was before lying down on the ground and closing their eyes one last time.
Deep in the palace, beyond the Staircases to Nowhere, on a scarlet bed, lay the Goblin King. His eyes were closed; they had seen their last upon a dark-haired girl many years ago. In his right hand was a pulsating crystal, its center filled with a glimpse of falling snow.