Tartarus was a prison used to hold some of the world's most dangerous monsters and criminals. Some of them had been there for only a few years, while others had been there for centuries or even more. Some criminals were kept in simple cells while others were placed in cages suspended over a seemingly bottomless abyss. Any attempts at escape that were discovered were stopped and those that attempted it punished. For the longest time the place was mostly maintained with powerful magics and an near-immortal three-headed guard dog named Cerberus. While there were mortal guards as well they were few and their purpose was more for warning the world that a prisoner had attempted (or more rarely succeeded) in escaping or delivering food and drink to the criminals than actually keeping them locked up. Realistically speaking the vast majority of those contained within were far too big a threat for mere mortal guards to deal with. But with the advent of the undead plague that had swept across Equestria and was now edging into other lands as well the prison of Tartarus was largely forgotten by the world. With fresh personnel rotation having ceased as well as no new food and drink supplies being delivered, even with strict rationing things were looking a bit grim. It wouldn't be long before their supplies were entirely expended.

There were twenty-six guards there currently. Most of them were ponies but not all. Originally there had been more of them, but when supplies stopped being delivered with no explanation given several had volunteered to set out for the nearest town to send a message to Canterlot to see what the problem was. They didn't come back. Correction, one came back, but she had been missing a leg and one of her wings looked like it had been chewed off by something. Perhaps several somethings if the different sets of bite marks were any indication. She also was very obviously dead despite still walking and taking rasping breaths. Her hide had been sagging and the eyes were as white as coconut milk. She was also being circled by a crowd of buzzing flies. After seeing that a few more guards left, all of them Pegasai. They first flew up to grab a few passing clouds, then also made their way to the town. A few days later they came back looking healthy but harrowed. If not for the undead Pegasus that had arrived earlier in the week the majority would have thought them crazy. Although they didn't know what caused it, the entire town had been turned into walking or crawling corpses. After resupplying themselves they then flew all the way to Cloudsdale and back to inform them that although Cloudsdale was mostly fine this was unfortunately spreading quickly. While the idea of checking in at Canterlot was broached, the Pegasai that had gone out to Cloudsdale warned against it, saying they had already considered that and had seen at a distance with binoculars hundreds of infected wandering the streets. Nearly half the number of Tartarus guards deserted their posts with that news, heading for home to see if their families were okay. As with their first scout group most of them didn't come back. The few that later did muttered quietly with haunted expressions that this was the only home they had to go back to and practically begged to resume their duties and be allowed back inside. This all happened a year ago. Two of those that had come back would later hang themselves.

Since then even with foraging from the surrounding area to stretch their rations their available food was running out. None of them had any talent with gardening or even keeping a houseplant alive which left them with few options. They'd long-since stopped giving food and water to the prisoners, seeing as it was only done as a courtesy of civilization in the first place and while in Tartarus proper they didn't need to eat, drink, or even sleep. It had occurred to the guards to starting living in there themselves and simply wait for things outside to blow over and someone living to come knocking on their doors, but with time and the rules of reality being a little strange sometimes in the holding areas some were afraid that they'd come out one day to find that they were the last living things on the planet. The idea of that scared them even more than the undead did. Even so, they'd need to make a choice sooner rather than later.

<><><>

Bottle Cap yawned and stretched his long sturdy legs before shuffling back into a typical 'at rest' position. The purple-eyed dark-rust-brown Earth Pony was bored. Beyond bored, actually. The prison had a small library's worth of books and crossword puzzles to keep the guards entertained while on break or on a day off but reading wasn't really his thing. They also had a small gym with plenty of equipment to stay fit when not patrolling the prison's halls or resting, but he was already one of the most fit Earth Ponies present. There were an assortment of tools for adding additional halls, rooms, cages, and cells to expand the prison's holding capacity, but with no additional criminals or monsters of any kind coming their way (other than the occasional shambling corpse, and that was not being brought inside!) for the foreseeable future and plenty of cells and cages already sitting empty and waiting it'd be nothing more than glorified busywork at best. "I miss parties and cider" he muttered, staring at the doors that were both the entrance and exit to the prison. Next to him and on the other side of the door a graying older Pegasus stallion named Butter Milk decided to add his own thoughts.

"I miss fresh pies and coffee, and a soft cloudy bed, and that pretty green-eyed blue mare across the street always up for a bit of fun once the sun went down." He faintly smiled as his mind took a stroll down memory lane. "I miss lively music and the smell of the air just after a rainstorm. I miss the happy faces of foals running down the street and playing with their friends or siblings. I miss-" he paused as the sound of hoof steps from several ponies on the chiseled stone floor echoed towards them. Both he and Bottle Cap turned their heads to see today's group of scavenger-ponies. As their superior officer was with them, they turned and saluted. He saluted in turn and stopped before them. Their commander, one 'Zip Tie' was middle-aged. His coat was a sandy color and his mane was cactus-green. His eyes were a slightly lighter shade of green and he looked tired, though perhaps 'worn' would be a better description.

"At ease. Any changes outside?" he inquired. Zip Tie was a former Wonderbolt that decided that the life of a guardspony was safer than that of a stunt flier after a bad crash during a performance broke almost every bone in his body. Had he wanted he could have kept performing after healing up, but while he was in the hospital recovering his parents begged him to quit for their peace of mind and he did. He didn't regret it...much.

"No sir." Butter Milk replied. "The sun and moon are still rising and setting, the rare corpse is still wandering by, and still no sign of any non-infected personnel here to relieve or resupply us. The weather is nice, though. It's a good day for flying."

"Small blessings are better than no blessings," stated one of Zip Tie's team. "Shall we go, sir?" Zip Tie nodded.

"Open the door, gents." Bottle Cap and Butter Milk nodded and approached the door, undoing the locks and turning the wheel-crank to open them enough for the squad of Pegasai to exit. After they were gone Butter Milk began turning the wheel again in the opposite direction to close it, but halted when someone yelled "Wait!" up the passage from around the corner. Butter Milk and Bottle Cap glanced at each other and Butter Milk shrugged and waited. The area near the door was clear of danger and had been for days so there was no risk from the undead getting in. Several seconds later a unicorn with a black coat and green mane and tail came around the corner followed by several others of assorted colors. They halted next to them.

"Has the food team left yet?" he asked.

"Sorry, you just missed them." Bottle Cap said. "What did you need?"

"We were hoping one of them would be willing to take some letters to family in Cloudsdale." A smaller mare in the back of the group stated, looking a little dispirited. "I've got an aunt there, and Cherry Pick has a brother and a grandparent there, too."

"Or at least I did have family there. I'd like to know if I still do." Cherry Pick held onto a letter of his own in a magical aura, looking worried and a little guilty. "I should have tried to send them a letter months ago, but between searching for food and seeing what happened to the town my parents were in...I don't think I could have handled it if it turned out they were gone, too." Others in the group nodded too and fidgeted with letters of their own in hoof or aura.

Butter Milk looked at Bottle Cap, then out the doors, and back at the group of dejected group of his fellow guards. Morale had been suffering around here pretty much since the very beginning of all this, and the longer things went on the worse it got. A little good news if there was any to be had could work wonders. I'm sure it would do the citizens some good to know that some guards are still keeping the dangerous monsters of Equestria in their cells, too. Butter Milk thought as he stepped over to Bottle Cap and handed him his spear. Bottle Cap gave him a questioning look and Butter Milk smiled and flicked his wings. Realization dawned but Bottle Cap gave him a questioning look, and glanced outside and gave half a salute. What will the commander think? He asked without speaking.

"Let me worry about that." Butter Milk said aloud, turning his attention to the small group in front of them. As if he were talking to them, he continued "I'll take your letters to them. Who am I looking for?" Eagerness bloomed from the gathering and one by one they handed him an envelope or scroll and gave a description of those they wanted their mail delivered to. Eventually he took to writing it all down, and finally stuffed it into a saddlebag before flying off into the sky.

<><><>

Meanwhile deep in the prison itself a trio of stallions seemingly meandered into the main prison area where some of the more recent menaces to society were kept. A Bugbear, a Manticore, a Chimera, and an assortment of other creatures and full-on monsters stared out at them as they strode by. Some of them looked resigned to their situation, while others menacingly glared out at them and prayed they'd be stupid enough to get within arm's reach. All of them were ignored as the stallions crossed the room to a set of stairs that led up to a pair of cages beside a ledge that dropped off into the abyss below. In one cage was an old and withered-looking Centaur that sat looking dejected in the center of his cage. In the other was a little pink Pegasus filly trying to squeeze between the bars of her cage to no avail. Both of them had several crimes to their name including murder, though those murders hadn't been directly intentional and more a result of not caring about collateral damage during their crime sprees. But intentional or not, dead is still dead.

"Back away from the bars, brat." One of the stallions spat as another of the three drew out a key to the cage.

"Golly, Mr guard! Am I being released?" Cozy Glow asked in a cutesy but sarcastic tone.

"Back. Away. From. The. Bars!" the same stallion repeated with a bit more bite to his tone. Cozy Glow offered a sickly-sweet smile and did as she was told. The third guard took out a set of hoof and wing cuffs sized specifically to fit her, and when the cage was opened they were put on her and she dragged out. Back across the room, back into a hall, and out into one of the older areas no longer used by Equestrians: the torture chambers. Here they wouldn't be disturbed. Equestrians didn't like this part of their past by and large, but they kept it anyway so they wouldn't forget it, and hopefully wouldn't repeat it. But because this was made during an ugly part of their history, this also meant that nopony went out of their way to see it unless they were a historian doing research...except for occasions like this.

"Uhh...you're not going to torture a little filly, are you?" Cozy nervously asked. She doubted that they would even with what she as convicted of, but why else would they bring her here and without a supervisor present? They didn't respond and instead removed her hoof cuffs only to attach proper manacles to her legs that were hanging from the ceiling. Now suspended uncomfortably in midair one of them turned a crank to lower her closer to the floor.

The stallion that had done all the talking so far lowered his eye level to hers.

"Cozy Glow the Pegasus. You tried to steal all of Equestria's magic. You came close to destroying civilization and quite possibly all life as we know it since there was no one able to control the sun and moon, and even though you ultimately failed your efforts made equipment both medical and otherwise stop working which led to multiple deaths to citizens of multiple ages across the nation." While he spoke there was a metallic clatter behind her but with a metal collar attached to a metal bar coming down from the ceiling also clamped tightly around her neck she couldn't turn her head enough to see what it was. "Do you feel any remorse at all, I wonder?" He rhetorically asked as he looked at her nervous face. Rhetorical, because he'd read her file and knew that her only regret was that she failed. Well, he and his friends would change that. By the time we're done with her, she's going to regret ever having had her ambitions in the first place! he coldly thought as he discarded his armor and his compatriots securely shut and locked the door.

Author's Note

I stopped watching the show about halfway through season...5, I think? Might have been 4, I don't remember. I did that mostly because people dropped so many spoilers while the show was running all over the internet that any of the important things to the plot I could find out just by reading or listening to that and save myself at least 15 minutes per episode. If there is something regarding Tartarus that doesn't align with what's canon to the G4 show, that's why. It had been mentioned a few times earlier in the show but there weren't many details other than 'it exists' until it was actively in it. I also did not watch ANY of the movies.
Finally, the part at the end with Cozy Glow is left vague on purpose. I'm sure you can come up with far worse things they could do to her than I could.