Beneath the earth, the sun is a forgotten concept. No sunlight filters through caverns, towers, and endless, crushing stone. Light is precious, flickering to life and burning out bright.
The Sunkeepers did not forget. They learned and perfected.
The Glass Sun hangs far above the Dead City's streets. Fist-sized from below, massive up close. Radium glow in filigree at "night", blazing blue in "day". Atomic energies bound by wards and lead alone. Surges and fades by the Keepers' whims, blinding by intensity and absence alike.
The Sunkeepers are a part of and apart from the world. Suits wrought from enchanted iron and lead hold the Sun's vital essence, joined to the body and trapped within. They burn to animate cinders that propel their ponderous gait undeterred. Without the suit, they are dissolute, barely-shaped gases of overwhelming heat. Burn bright in the heart of the Glass Sun, dim to a low, piercing glow when its hunger grows greater. Its emissaries prowl at the ebb of their own furnaces. They render their fuel from any source necessary.
Never speak nor write, but they understand. They trade with the City, but never for material; always for slaves. The Sun blesses the living. The Sun gives its blessing, accepted or not. So the Glass Sun grows.