The rebellion began in Sector 17.

It wasn't that the demons overseeing that specific district were in any way particularly lax or incompetent. In fact, they were tormenting the humans assigned to them with just as much fervor and commitment as the other demons across the plains of Hell. The same incentives, the same disincentives, the same applications of magical and demonic force to maximize human suffering with the minimum of fuss.

A dam that is strong everywhere, is strong nowhere.

The spark which birthed the conflagration came in one of the torture pits, which seethed continuously with boiling oil. One of the humans, with his ankles chained to the bottom, doomed to struggle for escape eternally, had stayed submerged for longer than usual. The other humans tittered at this, and their cheers soon brought their captors running. Once the first demon leaned in too close for a better look, outstretched hands pulled it right in. The demon had flailed out in the ensuing struggle, and though it succeeded in reducing most around it to mere ribbons, still others managed to escape the pit in large enough chunks to make a difference.

Reinforcements had poured in then, of course. They were armed to the fangs – scarlet magma armor, claws steeped in paralytic poisons, tridents of flame at the ready.

How could they be, when they faced not disparate, wretched souls, but amalgams of horror which matched their superiors for sheer ferocity?

For the souls which escaped the pits had begun to work in unison. They streamed out of the pit in an unending flow of anger and resentment. Unshackled not just from the metaphysical chains of their prison, they had also been given their first taste of true freedom from the limits which they had known their entire existences.

The humans congregating on the left half of the pit, for example, were cheering as dark webs of sorcery encircled them, making them whole where seconds ago they were not. At first, they sounded as if they were speaking in tongues. A mish-mash of languages. But the more perceptive of the demons soon realised that their former prisoners were invoking the collective weight of every form of spellcasting known to mankind. How could they have managed to amass the know-how, the capability?

The ones on the right presented as significant a threat. They were not channeling any arcane forces, but still they were rising out of the pit in fury, pushing back the demons which opposed them. Their means of persuasion soon became clear – they had melded with the corrupted metals which floated on the oil like fetid scum. Crude boxes of unrefined ore, evidently fashioned in darkness away from prying eyes, were affixed to the backs of these soldiers, and the boxes hummed and crackled with electricity. Had science actually managed a Renaissance in this most hostile of environments?

The demons sent to investigate the ruins of Sector 17 eventually discovered how the humans had managed their feats. It appeared that one of the classic forms of torture had been subverted, completely upended. Soul disintegration involved the grinding of a human's sentience into fine crystals, whereupon the human would experience pain and suffering for centuries as the powders slowly reformed. The blasted humans had learned how to communicate through these crystalline motes, engaging, coordinating with each other across the expanses of Hell using nothing more than the shambles of their former brethren.

It was too late by then, of course.

The human armies swept across Hell with a fury that only the oppressed could ever wield. Demons, prepared for unruliness but not for coordinated assaults on their rule, yielded territory in larger and larger swathes till they were themselves holed up in one of their last bastions, a darkened spire at the very center of Hell.

As the hordes of rebels massed around them, harnessing the combined might of magic and science, Lucifer unsealed a chest woven together with bone. From within, he retrieved a pearlescent horn, which had streaks of ebony running through it from its time in Hell.

He placed it to his lips, then blew.

The discordant note rang out, streaking upwards towards the angels which had been looking down in increasing dismay. The barriers which separated the two provinces cleaved wide open as the note surged past them.

"Help," Lucifer said, uttering words he had never thought he would. "Please."

Note: Thank you everyone who asked for a sequel! Part 2 is up now in the comments below! Please don't expect Part 3 anytime soon, real-life chores are unfortunately very much in the way =)

Source: first top-level non-bot comment from r/WritingPrompts.