In the days that followed, Leo abandoned his plans to roam the wasteland. Every waking moment — and even those when he simply stood, lost in thought — was given over to the crystal. At some point, almost without realizing it, he named it: the Radiant Crystal. And the strange, purified glow it shed, he called Radiant Energy.
Excitement buoyed him at first, lifting a heart he'd thought long dead. But soon, frustration crept in. The shard was painfully slow. Yes, it sifted the wild radiation, filtering poison into something gentler — but at a pace that mocked him. Millions, perhaps billions, of years before it made a true dent.
"Even for someone who has survived fifty thousand years," Leo mused, "that feels like an eternity."
He closed his eyes. 'Time is my ally,' he reminded himself. 'So why fret?'
The acceptance came not as surrender, but as a settling — like dust sinking after a storm. Impatience loosened its grip, and in its place curiosity bloomed. If this cavern had birthed one crystal, why not more? Give the world a few millennia, and perhaps dozens, hundreds, would rise. The thought pulled a rare grin to his lips.
"Right," he muttered, chuckling softly. "Must be rust on the brain."
In the meantime, there was work to be done. The world was still littered with vast caches of radioactive wreckage, relics he'd never bothered to retrieve. But now, they were more than waste — they were the fuel for something larger. He would gather them and haul them back here.
And someday, perhaps, he would stand upon a world that had begun — atom by atom — to cleanse itself.
***
At dawn, Leo began his descent, cradling the Radiant Crystal against his left side as though it had fused to him — as though he could no longer imagine letting it go. He wanted to see how it might respond to the world's last, forgotten remnants.
Every century or so, he made this same pilgrimage: down from Earth's highest point, across the scarred continents, into the planet's deepest fissures, before looping back again. The routine gave him purpose — or at least the illusion of it — and kept what was left of his mind from unraveling completely.
The trek never lasted exactly a hundred years. Sometimes, a shimmering vein of radioactive ore or an abandoned reactor complex would hold his attention for a decade or two. Other times, he lost entire months chasing subtle shifts in the planet's radiation currents, watching them spiral and drift like unseen tides.
He began, as always, on the eastern continent. Fifty millennia hadn't quite rearranged the plates, yet the coastlines had buckled, and new ridges rose where rivers and lakes had long since vanished. Following the faint tug of his internal Geiger sense, he unearthed pale blue ore streaked with uranium salts, pried molten-green diamonds from volcanic seams, and logged each find in memory, the way an old naturalist might press leaves between pages — except these pages existed only in his mind, and no one would ever read them.
From there, he crossed the contaminated ocean, noting newborn islets and the skeletal outlines of those that had slipped beneath irradiated waves. After visiting both poles — where frozen storms shimmered with deadly auroras — he turned toward the lowest point on Earth: the desiccated maw of the Mariana Trench.
Nothing should exist here. Once, it had been the ocean's deepest grave, cloaked in crushing pressure, darker than any light could pierce. But the oceans here were long gone — not fully vanished, but receded, boiled away, or drawn off to distant, fractured basins by the planet's slow, grinding collapse. The Mariana Trench now lay dry and exposed, its jagged cliffs jutting skyward like the fossilized jaws of some half-buried, ancient beast. Where water had once pressed and shifted the Earth's skin, only brittle rock and yawning fractures remained, stretching for thousands of kilometers across a silent, barren seafloor.
He always saved it for last. It felt like a cathedral of stubborn life. Though nothing complex endured, microbial colonies, fungi, and lichen clung to fractured rock, twisted into forms that fed on radiation-rich soil. Leo couldn't see the organisms, but he could feel their faint, collective pulse — the way a sailor senses the current beneath a keel.
Standing at the rim, he gazed down into a gorge that zigzagged across the crust like a colossal scar. Without a word, he stepped over the edge and let gravity take him. As he plummeted, the faint signatures of those hardy life-forms brushed against his senses, coaxing the barest hint of a smile to his lips. Pressure mounted as he fell, but the planet's grip had long ago lost the power to crush him.
He spent fifty more years in this place, testing, watching, waiting — searching for some reaction from the life-forms when bathed in the crystal's radiation. It all ended in quiet disappointment. But the disappointment passed quickly, like a cloud across the sun.
Now, Leo crouched at the trench's base, unbothered by the thin, toxic air or the searing heat that pulsed from the planet's depths. His pale skin gave off a faint, unnatural glow as his fingers traced along the warped walls, brushing stone no living creature was ever meant to touch. Over centuries, he had dug deeper, splitting apart the crust where tectonic plates collided, forcing his way into fissures where molten rock seeped and bled. What had once been a slow, drifting boundary had become, under his relentless exploration, a scar — carved open by hands that never tired and curiosity that never dulled.
He had found many things here: brittle remains of long-dead marine life, fossilized into delicate sheets; compacted layers of ancient sediment, telling stories no one was left to read. But what fascinated him most were the faint traces of radiation — contamination that should never have reached this depth, curling invisibly through the fractures, threading the stone like a poisoned whisper of the planet's ruined history.
Even here, at the bottom of the world, the fallout had sunk in.
Another motive kept Leo lingering along the trench floor: harvesting every pocket of highly irradiated debris he could find. Once he cleared this scar, he planned to race back across the globe, gathering caches he'd earmarked decades earlier and ferrying them all to Everest's cavern.
He paused beside a knee-high mound of glowing scrap — fuel rods, slag, mineral shards — scooped the lot into the crook of one arm, and turned to leave. Larger stockpiles waited elsewhere; he would need several wide-loop circuits to collect them all.
'Time is my ally,' he reminded himself, letting the words nudge his mood toward optimism.
With a single prodigious leap, he kicked off the trench wall, bounding from ledge to ledge until the gray sky reappeared overhead.
Neither sight nor sense alerted him to the moment the Radiant Crystal slipped from the bundle he carried and tumbled back into the abyss below.