Ash & Promethium

The Story Thus Far

The Fall of Hive Arcos

Extract from the sealed annals of the Arbitus Lexmechanic Vaults, Segmentum Obscurus. Clearance: Magenta-Oblivion.

Hive Arcos was once a jewel of compliant industry, its spires of ferrocrete and adamant rising like spears from the ash plains of Karthax Primus. For six millennia it fed the Imperium with munitions, promethium byproducts, and a steady tithe of flesh for the Astra Militarum. Its manufactoria never slept; its hab-blocks never knew silence. In retrospect, this constancy was the flaw that doomed it.

The first signs were small and easily dismissed. Production quotas exceeded expectations by statistically impossible margins. Shift-workers reported a sense of purpose that bordered on euphoria. Machine-spirits responded with unnatural obedience, ignoring litanies skipped and rites performed incorrectly. The Cult Mechanicus observers flagged these anomalies, but the data was buried beneath Arcos’ stellar output. The hive was too valuable to interrupt.

Then the sermons changed.

What had once been sanctioned exhortations to endurance and loyalty grew… personal. Lay-preachers spoke of liberation from suffering, of strength earned through sacrifice freely given. The language was careful, threaded with acceptable catechism, but carried an undercurrent that resonated far deeper than doctrine. The Ecclesiarchy delegation assigned to Arcos sent a single astropathic warning before communications failed entirely.

Within weeks, violence erupted—not in riots, but in rituals. Entire hab-levels went dark as populations vanished overnight. Arbites precincts were found intact yet empty, their occupants flensed and arranged in geometries that defied sane cognition. Vox traffic became polluted with overlapping whispers, machine-code resolving into shrieking laughter when decoded.

The planetary governor ordered containment. He never finished the decree.

When Imperial forces finally moved to intervene, they found Arcos already at war with itself. Manufactoria had been reshaped into temples of living steel and bone. Conveyor belts carried not shells but chained offerings. The hive’s defensive macro-batteries turned inward, annihilating loyalist strongholds with cold precision. Above it all, the spires bled—rusted tears running like veins, glowing faintly in colors not found in realspace.

Astartes intervention was authorized under emergency writ. Three companies deployed. None extracted.

What emerged from the depths of Hive Arcos was no longer human in purpose or form. The population had become a singular, howling devotion—each soul a note in a blasphemous choir, each death a prayer answered. Warp manifestations intensified to the point that the hive’s lower levels slipped partially out of phase, corridors folding into impossible angles, gravity and time behaving as suggestions rather than laws.

Exterminatus was considered.

It was denied.

Instead, by decree of the High Lords, Hive Arcos was shut down.

Void shields were raised and locked. Orbital stations were scuttled. The space lanes were recharted to bypass the system entirely. Automated kill-sats were emplaced with standing orders to annihilate any vessel—Imperial or otherwise—that attempted approach. The hive was declared Perdita Extremis: lost beyond recovery, its name struck from tithe records, its existence reduced to footnotes and redacted lines.

Hive Arcos still stands.

Its lights still burn behind dead shields. Its forges still turn. Vox-ghosts occasionally leak into the void—fragments of hymns, half-finished prayers, the sound of industry continuing without end.

The Imperium does not speak of Arcos anymore.

Ash Wastes Exodus

Recovered testimonies, scrap-cant, and enforcer briefings compiled under Subsector Edict 77-Theta.

When Hive Arcos was sealed, its void shields locking the damned and the loyal alike inside, those who escaped did not flee toward hope. They fled toward smoke.

Across the ash wastes of Karthax Primus, the only constant landmark was the burning horizon of Hive Alvearium’s promethium fields. Vast external refineries ringed the hive like iron thorns—towering fractionation stacks, pipeline forests, and flare pylons that burned day and night, painting the clouds in bruised orange and chemical blue. To the refugees of Arcos, those flames meant heat, industry, and life. They did not yet know they also meant chains.

The journey was a slow culling.

Ash storms stripped skin and memory alike. Promethium runoff poisoned what little water could be found, and the wastes crawled with rad-mutants and feral guild-scavvers who hunted anything that still looked human. The refugees learned to travel by night, following the flare stacks like false stars, hiding by day beneath slag sheets and broken crawler hulls. Those who began muttering hymns in unfamiliar cadences were silenced or left behind, their footprints quickly erased by drifting ash.

By the time the survivors reached the refinery perimeter, they were no longer a people—only remnants.

Hive Alvearium did not open its gates.

The promethium hive was a fortress of exclusion. Its ruling combines and fuel-guilds tolerated no disruption to output, and the taint of Arcos was already known in fragmentary astropathic warnings. Refugees were fired upon by perimeter turrets, dispersed by enforcer patrols, or driven back into the wastes with chemical suppressants and warning flares. Officially, none from Arcos were ever admitted.

Unofficially, many slipped through.

Maintenance culverts beneath the refineries ran deep and wide, choked with fumes and runoff but poorly monitored. Smuggler ducts, pipeline crawlspaces, and waste-heat exhaust shafts became arteries for the desperate. Those who survived the toxic labyrinth emerged into Alvearium’s lower rings—scarred, half-mad, and utterly illegal.

There, they clustered.

Former hab-block neighbors and shift gangs reformed as ash-clans, bound by survival rather than loyalty. They lived nomadic lives along the hive’s under-rings and refinery skirts, raiding fuel convoys, stripping pipeline junctions, and tapping promethium lines with crude siphons that killed almost as often as they fed. Their skin was stained orange-black from chemical burns; their lungs rasped with every breath. Many bore the sigils of Arcos cut into their flesh—not as devotion, but as a reminder of what a hive could become.

Hive Alvearium’s Enforcerium classified them as roaming criminal elements: vagrants, saboteurs, fuel-thieves. Purges were frequent, brutal, and rarely complete. The ash-clans scattered, reformed, and learned. They memorized patrol routes. They worshipped silence. They taught their children how to run along pipelines without slipping into the fires below.

Some clans began to believe that Arcos had not followed them—that they had escaped its curse. Others knew better. They spoke of dreams where the refinery flames burned the wrong colors, or where the pipelines whispered in familiar voices. Those clans never lasted long.

Today, the Ash-clans of Alvearium persist in the margins—unregistered, unwanted, and uncounted. They fuel the hive even as they are hunted by it, living off the lifeblood of promethium while knowing that, one day, the flames may turn inward here as well.

Because they remember Arcos.

And they know that no hive burns forever without eventually burning itself.

Ash and Promethium

In the years following the sealing of Hive Arcos, the Administratum marked the disaster as contained, its records sealed and its tithe lines struck through with red ink. The truth sank downward instead. It bled through the ash wastes, crept along forgotten transit lines, and finally pooled in the depths of Hive Alvearium.

Alvearium is a hive built to burn. Its outer shell is ringed with colossal promethium refineries—towering flare stacks, distillation spines, and pipeline webs that roar without pause. Firelight stains the sky a permanent orange, and the air reeks of fuel and industry. Order is enforced not out of mercy, but necessity. If the promethium flow falters, worlds die.

When refugees from Arcos reached Alvearium, they were not welcomed. The gates remained sealed. Enforcer patrols drove them from the light of the refineries, and the fuel guilds issued quiet kill-orders against any sign of Arcos taint. Yet the hive is vast, and no wall is perfect. The desperate slipped inside through maintenance ducts, pipeline crawlways, and waste vents—emerging far below the hab-rings, deep in the Underhive where law thins and survival becomes currency.

There, the remnants of Arcos fractured into gangs.

They had no Houses to shelter them. No supply chains. No legal claim to territory or trade. Their weapons were scavenged from scrap piles and corpse heaps: cut-down autoguns, refinery tools repurposed into axes, pistols held together with prayer and wire. Ammunition was hoarded, armor patched, and every piece of functioning wargear was worth killing for. These Outlaw gangs fought not for power, but for space to exist, moving constantly through the lower levels to avoid annihilation.

Above them, Alvearium’s sanctioned gangs and forces tightened their grip.

Law-Abiding gangs operated with the blessing—spoken or implied—of the hive’s rulers. They drew on steadier supply lines, cleaner arms, and the authority of the hive itself. Their mandate was simple: protect production, secure the Underhive, and ensure that what happened to Arcos never happened here. Every Outlaw cell uncovered was a warning, every purge a lesson written in blood and flame.

Thus the lines were drawn. 

The Underhive became a battleground of scarcity and control. Outlaws struck from the dark, desperate and under-equipped, knowing that each loss was irreplaceable. Law-Abiding forces pressed downward with superior arms and numbers, but never without fear—because Arcos had taught them that corruption did not announce itself until it was already too late.

In Hive Alvearium, the promethium still flows and the flare stacks still burn. But in the depths below, amid ash, fumes, and ramshackle gunfire, the legacy of Hive Arcos refuses to die.