The asteroid called 1999 RQ36 had only had a one-in-one thousand chance of striking the Earth. Earth's scientists were aware of this asteroid and quite concerned about it for a very long time. Luckily, they had methods with which they could deflect the asteroid, and were aware of the dates on which they needed to do it.
But, as providence—or the lack thereof—would have it, the scientists did not do anything about it. Nobody but the scientists was all too concerned, so publicity and funding were hard to come by. Everybody needed them to be doing other things, and everybody seemed to assume that when the time came, they would be able to send Bruce Willis and Chuck Norris into space with a nuke and be done with it.
Unfortunately, when the time did come, Misters Willis and Norris were unavailable; against all odds, 1999 RQ36 struck the Earth in the year 2182. The Earth had survived 2012, but not 2182.
Granted, it may have survived if the ethereal and occult inhabitants of Heaven and Hell had not decided to take advantage of the calamity and finally get around to that little war they'd been meaning to have. But they did have their war, and there was nothing any inhabitant of Earth could do about it.
This category included Aziraphale and Crowley. For this certain Apocalypse, they were left completely out of the loop until the very last second. The new Antichrist was very enthusiastic about the end of the world, as he had been allowed to live a long and unhappy life until he was needed. And so the war was fought. Humans died gradually and usually painfully, either from freezing or starvation or as a result of the supernatural war. All marks of their presence on Earth were destroyed by the fighting. Eventually everything was rubble, and all the humans died and were shuffled off to their new eternal homes.
Crowley and Aziraphale remained on Earth the entire time, even after their human corporations were destroyed.* But they never fought, not with each other's and not with their colleagues. They traveled, trying to avoid the war as much as possible over the course of the Seven Years. At the same time, they tried to avoid humans as well. The other angels and demons fought right out in the open, so winged beings of both kinds were terrifying to people. The few times Aziraphale and Crowley came into contact with people after losing their corporations, they were attacked.
So they stayed in ruined, deserted cities with endless bottles of wine in their fists, out of the way until the very last hour on Earth.
*The roof of their cottage had collapsed on them when a gang of demons slammed an angel into it in the middle of the first year of the War.
At the end, it wasn't exactly clear which side had won the war. Once Aziraphale and Crowley met up with their fellows, the only thing that was clear was that the surviving angels and demons were to return to their own realms and never leave again. And they were calling for Crowley and Aziraphale to finally join their ranks again.
"Well, that sounds like a great idea, I won't lie," Crowley lied, his fingers tightly intertwined with Aziraphale's behind their backs. He was looking at the demons with a manic, nervous little smile, and it flitted through his mind that the demons had made themselves much more monstrous-looking just for this war. Likewise, all the angels had tall, muscular, perfect, identical bodies, with long, lush hair, complete with halos, robes, and heavenly glows.
Whereas, Aziraphale and Crowley appeared more or less as humans, just with large, strong wings jutting out of their backs. Shirts, pants, jackets. Neither of them was even carrying a weapon.
Their lack of flare unnerved Crowley as he continued, "No, really, it would be an honor to be banished to Hell with you guys like a real soldier of Satan, but unfortunately, guys, I'm not one. I'm a pretty nice damn guy."
Aziraphale nodded vehemently. "Oh yes, he's really a pathetic little excuse for a demon. You lot wouldn't want to be stuck with him for the rest of eternity. He wouldn't even help you torture the damned humans." He turned his eyes to the angels, who were regarding him with nearly as much distaste as they bestowed upon the hell-spawn, which triggered an instinct inside him that made him just ramble. "Of course, the same goes for me too, fellows. I eat and drink much too much, and I really, really like sex." He coughed delicately into his fist as Crowley snickered. "The point is, you'd get awfully sick of me in no time at all. So I really can't accept your invitation to go back Up There."
A voice finally piped up, low and unrecognizable. It wasn't readily apparent whether the voice belonged to a divine or a demonic creature; since they weren't fighting, their forms had begun to change again, and everyone sort of just blended together, making it damned well difficult to tell who was what.
"But where will you go?"
Aziraphale and Crowley must have been blending together in the eyes of their peers as well, like they didn't even seem to count as two Beings anymore. So they went along with it and spoke for each other, their answer having been long since decided upon.
"Limbo," one of them answered, squeezing the other's hand. "You can't say we really belong anywhere else."
A murmur went through the crowd. Vaguely inhuman eyes flitted on and off the two misfits, their owners trying to decide how much the two mattered in the Long Run. Wondering if it would be worth it to stop them or if they had any right to.
"I mean, it's not like we lived Up There or Down There for longer than we lived Right Here"
Another voice, this one slightly easier to peg as angelic, directed a question towards Crowley. "And you're sure you're not just going there to avoid Eternal Punishment?"
Crowley actually laughed. "Are you kidding? I'll be stuck Over There with a bloody angel for the rest of eternity. I call that punishment enough." But he ran his thumb over the back of the angel's hand.
It felt like somebody should have directed a similar question towards Aziraphale for symmetry's sake, but nobody did. Because, really, his actions made so little sense that nobody could even begin to fathom a good enough reason for him to turn down the Everlasting Light of Heaven. Not even when the reason was standing right next to him, holding his hand like a lifeline and fingering the gold ring he still wore after all these years.
So the tweed-clad angel just cleared his throat and said, "Yes, well, there you have it, I suppose…Er." He paused and looked at the faces of the angels, his brethren, and attempted to call up some small feelings of bitter-sweetness, to find a face that he would miss after he'd gone to Limbo with no way back. But he failed. The only face he would ever miss, he would never have to miss. So he gave a little sigh and finished, "Well, goodbye, then."
"Ciao," said Crowley, waving tauntingly.
And then their images seemed to dim a bit, shift an inch or two, and flicker a few times.
And then they were gone.
Metaphysical environments are formed by the collective Will of their inhabitants. Human Will is strong enough as it is, but the Will of supernatural beings is even stronger. So when Crowley and Aziraphale joined Limbo's population, the environment obeyed their wishes, which were certainly more specific than the vague desires of the dead humans.
Limbo was similar to Earth, this was true, but only enough for the humans to be comfortable until their return to the living world. They didn't know enough to have a very solid existence; transience was intrinsic in the culture. Cities would ebb based on the latest generation of dead people, technology would improve by uneven measures. Nothing was set in stone.
But when the angel and demon made it their home, things changed—changed in that things stayed the same more often than not. The realm was now formed around what they wanted out of it; which, surprising to say, was not the world of the late 22nd Century. No, the world their paradise was based on had existed around two centuries earlier on Earth—the world of ansaphones and petrol-run cars and cassette-tapes. It had been a good world back then, one before teenagers ruled pop-culture and before every piece of technology had games built in.
It was a world they could spend eternity in, a world that, once upon a time, they'd feared to be the last one they'd ever see.
Some years they would allow the Time to shift, sending them into centuries past or future. The humans didn't mind. They adapted happily into Roman garb or Victorian threads*, not sparing a thought to how their language or customs changed from year to year. But most of their time was spent in the late 20th century, so their lives were stable enough.
*Aziraphale thought that this would be a good experience for Crowley, who had slept through nearly the entire era.
Before the real end of the world, humans in Limbo were in a sense insentient, unaware of their past lives, and unaware of the fact that they were soon to move onto a new one. They were stuck at the age of their last passing, forever waiting—but unaware they were waiting—for the next life. There was no death, no birth. It did not register in their hazy minds when a new soul entered the realm or when one moved onto the next life on Earth. It happened so often that nobody created any bonds to anybody else.
But, now that there was no Earth to move on to, things changed. Now it was practically as if they were living again, as if this was Earth. They aged, they loved, they died. But the cycle of reincarnation was instantaneous, so as soon as they died, they didn't even have time to worry about the state of their soul before they were thrust into a newborn's body. Their memories were more or less wiped, and they started living again. Each life was so different that it was impossible for Aziraphale or Crowley to become bored with this slightly-deceased human race. They continued their old habits of tempting and inspiring, although it did not matter in the least what a person did anymore, seeing as all paths to any other realm were now completely nonexistent.
Aziraphale and Crowley were creatures of habit if nothing else, beings who sought normalcy above all else. So this new existence made them happy beyond compare. For the first time since Creation, they had control over their own destinies and were free to share their destinies with one another—without fear and without end. Nothing would ever take them away from the bookshop or the Bentley or the cottage or anything else in the damned, blessed world.
And it was good.
Erin here. Well, fellows, this is finally the end. I didn't mean to leave this fic hanging so very long without a proper ending, so here it is. I hope you all like it. The bare bones of this have been on my hard-drive for well over a year, I think, lol. As it is, I think that if I ever write any more Good Omens fluff, it will be part of a different overall fic. I just want this one to be rounded out. Thanks so much for all of you who have read this.