apocalypse - (n.) 1. an event involving great and widespread destruction. 2. (the Apocalypse) the final destruction of the world, as described in the biblical book of Revelation.

origin - Greek apokalupsis, from apokaluptein 'uncover, reveal'.

*

The first time Jack Harkness saw the end of the world, his name wasn't Jack Harkness and the world in question was one of Earth's most distant colonies. He was still a boy, innocent and naïve about the ways of the universe until They came and destroyed everything he cared about.

He didn't realize what was happening at first. There were rumors of deaths on other worlds near the Boeshane Peninsula, the numbers too high for a child to even imagine, but there had been no names, no proof, nothing but tales told by haggard-looking refugees. While the adults had whispered to each other in hushed voices using words like "apocalypse," he and Gray had played games, stealing their ideas from the ancient stories their uncle kept in his digital library. Stories about beasts, and seals, and horsemen fueled their imaginations for almost a year.

Then both Gray and his father became two of those formerly unnamed victims, and they stopped being faceless statistics.

Later that day, as he wandered along the paths that he had known his entire life, trying to wrap his mind around what had happened, he finally understood what the adults had meant by "apocalypse." Bodies rested where they had fallen: old and young, male and female. The enemy was indiscriminate in their killings: people who he had known his entire life; schoolmates he had kissed between classes, practicing his techniques; strangers simply passing through on their way to the nearest city. There was nothing left but blood, and tears, and whispers that the government was sending refugee ships before the enemy decided to come back.

The next day, he flirted his way onto a transport ship that was heading to the nearest military center. He wouldn't technically be old enough for another three months, but things like birth certificates were fairly simple to fake if someone put one's mind to it. Of course, the blowjob he gave his recruiter didn't hurt either.

*

The second time Jack saw the end of the world, he helped cause its destruction.

It was his fourth year with the Time Agency and his sixth month partnered with the man who would one day go by the name of John Hart. Someone had traveled back in time to the end of World War IV, apparently bent on changing history. The woman had almost stopped the Pan-American government from using the nuclear weapons that finally ended the war before they arrived to put things back on track.

"Consider it a gift, hotshot," his partner had said, grinning as he grabbed the younger man's hand and pulled it up to rest on the yellow button on the console. "This is your chance to become a part of history."

Something deep inside him had wanted to recoil and insist that they follow regulation. He was the junior partner; it wasn't supposed to be his job to do the dirty work. Except he knew his partner well enough to understand that the other man thought he was giving him a gift. So he grinned back, hoping his nervousness didn't show, and pressed the button - trying the entire time to convince himself that it was a fixed point in history; it would have happened anyway. It wasn't his fault.

Later, once they had debriefed and received two weeks' rest before their next assignment, he had pulled up an article on WWIV from the database. Two billion killed in the nuclear holocaust that followed the war's end, almost a fourth of the Earth's population at the time, the name and picture of every single one of them listed if anyone was of the mind to look them up. Nobody ever did, save the occasional student studying the war.

Not for the first time, he wondered just what he had got himself into. Then he spent the next two weeks making his way through as many names on the list as he could; he owed them that much.

*

The third time Jack saw the end of the world, it was the Doctor's fault.

After leaving World War II behind, the first place that Jack had traveled in the TARDIS was a small café in Bristol in 2257. There he, the Doctor, and Rose spent two hours eating chips, swapping detailed stories that told the others absolutely nothing about themselves, and terrifying all of the other customers. They probably would have stayed longer if it hadn't been for the alien invasion, but the TARDIS being stolen had turned the Doctor's mood sour fairly quickly.

The second place the Doctor took them was London in the middle of the Black Death.

At the time, Jack hadn't understood. As he and the Doctor walked through streets that were empty except for the bodies that littered them, Rose safely behind on the TARDIS, he assumed that this was a punishment for the Chula nanogenes and carefully kept his discomfort hidden. "Sometimes everybody dies," the Doctor replied, his face expressionless, when Jack finally worked up the nerve to ask him why they were there.

It wasn't until much later, when Jack saw people at Torchwood - people he almost considered friends - die in the influenza epidemic of 1918, that he realized it hadn't been a punishment. It had been a lesson. People died; that was a fact that he couldn't change, no matter how much he wished he could.

Jack had had nightmares for weeks after that trip to the fourteenth century, memories of life in the Boeshane Peninsula haunting his dreams for the first time in almost a decade. It wasn't until the Doctor offered to take them to an infamous strip club in the 64th century, the look on the Time Lord's face almost apologetic, that Jack realized maybe he had misjudged the Doctor.

*

The fourth time Jack saw the end of the world was technically the fifth, but he supposed it really didn't matter since it was simply him living through the same apocalypse twice. Besides, the first time through hadn't quite seemed real, since he had spent it in chains with nothing but a small television screen to link him to the destruction taking place around the world.

He knew that something was wrong the moment he came out of stasis. The timing should have been perfect; he would be gone just long enough to convince Gray that his plan had worked, that Jack was out of the question, but not a minute longer. Except the Hub didn't look right. It was too quiet, too dark, too dirty. He hadn't been gone long enough, relatively speaking, for its appearance to change that much.

Plus there was a fucking Toclafane, half-dissected, sitting on the autopsy table. Not to mention a large pool of dried blood on the floor beside it.

It took Jack less than five seconds to realize what had happened. "The Year That Never Was," he said softly, his voice hoarse from disuse as he repeated the name that the Doctor had come up with for the year of the Master's reign on Earth. Or had it been Martha? It had been too long. Though he supposed it didn't matter in the end. He had woken up in the right place, at the right time - just in the wrong version of the year.

Behind him, something clattered on the floor. Jack spun around, his hand already reaching for his gun.

Ianto was standing there, staring at him like he was a ghost. He was wearing jeans and a T-shirt instead of his usual suit, his clothes and skin both stained with dirt and blood. "Jack?" he whispered.

Two weeks later, this Ianto would be dead, his body brought on board The Valiant in an attempt to break Jack's past self. Less than a month after that, it would be over - time would reset, and Jack knew that he would find himself back in stasis, his memories of this completely erased. He would wake up in May 2008, as planned, just in time to stop Gray (save Gray), hug his team, and get back to the life he had made in Cardiff. His choice was simple: he could simply go back into stasis, wait for the reset, and not even worry about the apocalypse going on outside the walls of the Hub; or he could spend the next five weeks hiding from the Toclafane and the Master, walking among the piles of corpses that littered the world, making certain that he didn't get captured since he wasn't sure if even the Paradox machine had its limits.

"Jack?" Ianto repeated, his voice shaking as he took a step closer.

Jack covered the meter or so between in two steps, grabbing Ianto and pressing his lips against his like his life depended on it. It didn't matter that this wasn't the same Ianto Jones he remembered, the one who had shared his bed for months. This man had seen so much death yet still managed to survive.

It really wasn't even a choice.

*

The fifth time Jack saw the end of the world, he was the only living thing left on Earth. He had grown up hearing stories about humanity's temporary exile from Earth after solar flares had destroyed everything, and everyone, who hadn't been able to escape in time. He had read about how the Space Station Nerva had been put into orbit around the planet, keeping those who hadn't wanted to colonize other worlds in cryostasis until it was safe to return. His own colony in the Boeshane Peninsula had been established during that time, in the aftermath of the Unification War that had marked the eventual downfall of the Alliance that had kept humans from returning to Earth for so many centuries.

If he was honest with himself, his visit to Earth - his first trip back in at least three centuries - had been based on purely selfish motives. It wasn't that he was trying to die, per se, but he figured it didn't hurt to at least make sure that intense solar flares wouldn't kill him. What kind of friend would he be if the Doctor showed up and asked him to go diving into a sun, only for him to actually die in the process? The last thing that particular Time Lord needed was more guilt.

Unfortunately, Jack hadn't quite thought things through. He had known from the history texts that everyone hadn't made it off the planet before the radiation levels rose too high to support life, but everything he had studied so long ago had made it seem so . . . sterile. He had expected the planet to be a wasteland, nothing remaining except scorched earth and his memories.

There were bodies everywhere, half-decayed and burnt from the flares, but still there. People, and animals, and buildings, and vehicles. It was a dead world, and as memories of all the people he had loved and lost over the millennia rushed through his head (don't forget me), he could understand why the humans of the time had been so certain that this was the end. If he hadn't know that it wasn't, known that no matter how bad it seemed things would eventually get better, he would have believed it as well.

An hour later, Jack discovered that apparently solar flares could be scratched off the list of things that might possibly kill him for good. It had been worth a shot, at least.

*

The last time Jack Harkness saw the end of the world, his name wasn't Jack Harkness and the world in question was nothing but a shattered shell of the planet that he had loved for five billion years.

As Earth was swallowed by the sun outside the protective shielding covering Platform One, the Face of Boe closed his eyes. For just a moment, time seemed to stand still. For the first time in millennia, he remembered. His parents. Gray. His fellow Time Agents. The Doctor. Rose. All those bright, handsome, young men and women that he had lost during his years at Torchwood. Friends. Lovers. Husbands. Wives. Children. Strangers.

How many times had he seen the end of the world, only for humanity to pick up the pieces and find its way back through the dark? How many times has he thought he'd lost someone forever, only to receive one more chance to say his goodbyes?

It had been a blessing and curse to see them again: Rose, looking so impossibly innocent, and the Doctor, his first Doctor, completely unaware of his true identity. At least now he knew that he was no longer a constant, out of step with Time herself; there had been no disgust, no recoil from the Time Lord who seemed so young.

The last time Jack Harkness saw the end of the world, he realized it wasn't the end. He had seen the future, walked through the cities of New Earth, and New New Earth, and even New New New Earth during his time at the Time Agency. He had been to the end of the universe with the Doctor. Humans had survived even then. Life had found a way.

He opened his eyes. Outside, the Earth had completely vanished. Sol had swallowed her, wiping away five billion years of history - but not a single life.

It was the end. Time to begin again.