The first nest Crowley built took form around 42 AD, in Rome. He and Aziraphale had been stationed in the city for a full year at that point, running into each other every other week as their temptations and blessings led them from one side of it and back again. There had been a number of shared dinners, late night walks and cups of fine wine. More than ever there had been before, if not as frequent as they one day would become.
"Paying people to cook for you is such a wonderful invention," Aziraphale had said in an unguarded moment, "I'm so glad it caught on."
It were those moments, those glimpses of opinions and free will and preferences, that had snared Crowley. From their first encounter in the Garden and through the following millennia, Aziraphale's tantalisingly unangelic qualities drew Crowley in like flies to honey.
His angelic qualities were alluring as well, if Crowley were to be honest with himself, but Crowley rarely were. At least not back then.
"I can't wrap my head around this slavery business," Aziraphale had said another time as they'd ended up in the audience at the same fighting pit, neither of them enjoying the show. "Did your people come up with it?"
"No, this one's all on the humans," Crowley had answered. He'd long ago come to terms with the fact that humans had demons beat in the field of creative evil; beat by miles, if not continents. "I'm sure they'll get over it," he'd lied, because Aziraphale had looked genuinely distressed and even back then Crowley couldn't take Aziraphale's sadness for long, much less genuine grief. "You know what? Why don't you take this one."
"Sure, why not," Crowley had said, done his best to hide his racing pulse, and then decided to just not have a heart for the rest of that afternoon. "I'm bored. Go free some slaves, I'll find something better to do."
And so the days in Rome passed them by. Wine, food, theatre, and the occasional blessing, temptation, miracle and curse.
Semi-consciously, Crowley had begun contemplating the fact that the two of them seemed destined to cancel each other out; a thought that rooted itself deep and steadily grew into the idea that would become the Arrangement. Subconsciously, he'd begun furnishing a house.
Well, decorating a room. Though it wasn't so much the decorating that was subconscious as the reason behind it.
Crowley hadn't yet gotten the hang of sleep so had no real need for permanent shelter. Despite this he'd been gifted a domus during the unpleasantness the year before  and had seen no reason to not accept it. After he'd gotten rid of all the servants and slaves  it ended up a good place to bring Aziraphale when they wished to converse away from prying eyes and ears. The angel would never stay for long, but his visits still numbered hours, if not days of time in total, that surprisingly lovely year in Rome.
During the hours after Aziraphale had departed the domus, Crowley would find himself shedding feathers at an unusually rapid rate.
Wing grooming hadn't really been a thing before time had been invented. Angels hadn't needed shape or substance before God had gotten working on Creation, and once the angels had begun to take shape said shapes tended to stay the way they'd been asked to, until time became a factor.  With the passage of days, months and years thrown in the mix, both angelic and demonic wings ended up losing feathers, growing new ones, and getting rumpled.
Crowley had gotten into the habit of tending to his own wings every now and then, to keep them in good shape. Getting at all the feathers wasn't the easiest thing, but when you had actual miracles on your side it wasn't impossible. He'd quickly come to see it as another part of maintaining his vessel, a vital step in keeping it in tiptop shape.
The addition of a sudden need to hold on to the moulted feathers thus didn't alarm him, at first. He kept them in one room of the domus near the back, stored in jars, and made sure Aziraphale never saw. It felt private, somehow.
Then many things happened, as things tend to do, and before long (give or take a few decades) Crowley found himself in a completely different part of the world, given missions far away from Aziraphale. The domus had long since been levelled to the ground and the feathers burned during some war. At this destruction Crowley had felt a faint, strange sensation of loss that he'd never experienced before when leaving a place. It unsettled him. Going around missing parts of Creation wasn't something a demon should do.
They shouldn't miss angels either.
The second nest saw the light of day just a hundred years after the first one. A century may seem a long time, but for an immortal a century can pass by as quickly as a week, if one keeps oneself busy. Crowley had been kept very busy and also hadn't crossed paths with Aziraphale too often (that is, not as often as he'd have liked to), so the century had more or less flown past.
Then he and Aziraphale had ended up ordered to influence the same rival chieftains.
The mission on its own had been terrible. They'd been stuck in a cold and wet land called something Crowley quickly forgot (or pretended to forget). The locals had been suspicious of strangers, especially strangers who kept their eyes hidden. The food had been awful. But despite all this, he'd seen Aziraphale almost every day for a whole year, and that made up for all grumbling humans and rainstorms in the world.
Once Crowley had established himself, he'd ended up getting a tent; a cramped affair with little room for more than sleeping. The walls ended up covered in feathers within the first month.
Sadly, the tent got buried in a mudslide of Crowley's own making. That trick helped him finish his mission, but all his moulted feathers were lost and Aziraphale left the valley without as much as a goodbye. It didn't matter that Crowley had done his best for them both to succeed at their missions . Heaven clearly didn't appreciate half-finished projects, which Crowley really should have remembered, having lived there once.
He barely noticed the loss of the nest, that time, because Aziraphale giving him the cold shoulder stung far worse.
It took almost two hundred years to get back into the angel's good graces. Not that Aziraphale outright shunned Crowley; that would have been unbearable. But he kept hesitating, rarely stayed too long in his company. As if Crowley couldn't be trusted.
This should have been the natural order of things. Demons didn't trust other demons, so angels absolutely shouldn't.
But Crowley found that, above all things else, he wanted Aziraphale to trust him. He also wanted Aziraphale to talk with him and walk with him and drink with him and eat with him and… and…
The gift giving began then. Not outright giving per say, but there had definitely been gifts. Crowley took a deep dive into all the things Aziraphale enjoyed and came up with details he'd previously been unsure of; what Aziraphale's favourite wine was, what entertainment he sought out most, what food delighted him more than other options. When he'd amassed enough knowledge to anticipate Aziraphale's interests, Crowley 'just happened' to take them to places where such things were available.
He also may or may not have had things left at Aziraphale's current dwelling 'on accident'. People dropped things all the time. It was hardly strange that clumsy people lost their things outside (and on two occasions, inside) Aziraphale's home every other decade, now was it?
"Humans can be so strange." They'd been in Istakhr, overseeing a union that both Hell and Heaven found important, though neither Crowley nor Aziraphale were ever told why. "Yesterday, a boy dropped a wreath of flowers right outside my home, but when I called after him he said he hadn't been paid to pick it back up again. Isn't that odd?"
Crowley couldn't help himself, because he never could, so he asked: "That why there's a wreath decorating your dwelling now? To help its owner find it?"
"It is a lovely wreath," Aziraphale had said, pointedly avoiding eye contact. "I couldn't leave it lying in the dirt. That would have been tantamount to a crime!"
On rare occasions, Crowley knew when not to push his luck. He'd thus made no comment about how the flower wreath had blooms never seen in that part of the world or how he knew said blooms to be some of Aziraphale's favourites. Green growing things weren't one of Aziraphale's main interests, but he did have certain plants he liked more than others, and it had seemed…appropriate to give him flowers, the previous day, even if Aziraphale wouldn't know it was a gift.
Said previous day had marked the 42th century of their acquaintance, but who was really counting? 
A handful of years after that conversation, Crowley's careful approach bore fruit. They still didn't see each other too often at this point in history, every other decade or so, but when they did Aziraphale would greet him with a smile.
Being welcome had never felt that good before.
"Ah, Crowley!" Aziraphale would say, patting the seat next to his, or making room for him at a table. Or he'd spot him across a crowd and give a jaunty wave, before he remembered himself and feigned a lack of recognition.
Crowley let him. If a poor pretence that they didn't know each other was what made Aziraphale feel safe sharing food and words with a demon, Crowley would happily play along.
Well, maybe not completely happily. But play along he did.
By the third nest, Crowley had begun catching on that his behaviour had a drive behind it. See, he never had the urge to find a place to live unless Aziraphale was nearby. He definitely didn't start raining feathers every which way when he took up residence somewhere, unless he'd recently seen Aziraphale.
It had taken him a good four hundred years, but he finally put the pieces together. And then he cursed a lot.
"This is a joke, isn't it?" Crowley found himself hissing at the sky. "Like I'm some blessed bird, doing that - that thing that birds do! Prancing about, building things, trying to-." Here Crowley ran out of words and choked a bit.
That nest he burnt. The pain of losing it echoed well with his rage and shame, so for once he welcomed the destruction.
Still, many other nests followed it. As did many other gifts. Human or bird or what have you, courtship seemed an inevitable instinct that had been thrust upon Crowley. He couldn't stop his wings from moulting any more than he could stop himself finding interesting food and new entertainment for Aziraphale to sample.
He was lost to it, and he knew it. He couldn't make himself regret it. How could he when he got to watch Aziraphale laugh at jokes and beam as he ate new food?
He also couldn't stop himself from wondering if nest building had been a joke played on fallen angels only, if it had been a punishment for him in particular, or if it, maybe, just maybe, applied to all of angelic stock?
There were no nests in Hell and he doubted there were any in Heaven. But perhaps - and here Crowley cursed his own optimism as much as he clung to it - perhaps it was an instinct shared by angels and demons who'd stayed on Earth long enough?
When the Arrangement took its start in 1020, Crowley began looking for signs of Aziraphale settling down. Unlike Crowley, Aziraphale had from the start been quick to find himself a dwelling among humans, preferably a comfortable and cosy one, but also seemed happy to give up said dwelling and move on at the drop of a hat. Crowley tried to mimic this behaviour best he could now that they were meeting up every other year and failed miserably. Being around Aziraphale this frequently had him itching to find a fitting building and coat it in feathers, hole up there until their next meeting and just be.
All their meetings happened in public places, preferably in crowds or in shadows or both, as had become their habit. The main difference from before was that they now sometimes met up to plan ahead. While previous chance meetings sometimes had gone on until a shared dinner or walk had been won out of it, these meetings now started with such things. They met up at places they both enjoyed (well, mostly places Aziraphale picked or places that Crowley picked that he knew Aziraphale would like) and there they planned, shared their burdens, and Crowley gently, careful pushed for more time with the angel.
The only years from 1020 to 1299 that Crowley didn't have a nest in the works were the years assignments kept them apart for more than a handful of months. Each time Crowley saw Aziraphale abandon a house or a hut or a tent, he disassembled his current nest and set fire to the feathers he'd saved up.
It wasn't time. It was never time. The nests were never good enough.
And yet he kept building them, one more complicated and detailed than the next. Feathers weren't enough any more, he needed a place they both would like. A place in which Aziraphale would enjoy spending time.
Crowley rarely started from scratch, but he tried all manner of buildings and architectural styles. He tried steering conversations with Aziraphale onto the topic of human homes and what Aziraphale might like or dislike about the current style of living the locals had created. What aversions Aziraphale voiced, Crowley made sure to banish from his latest work in progress.
Then the 14th century rolled around. There were no nests during the 14th century.
"Is it ever going to stop?" Crowley had asked Aziraphale, standing at the edge of yet another dead village.
"It must," Aziraphale had said and looked for all the world as if he wished to reach out, place a comforting hand on Crowley's shoulder or take his arm. Or maybe that had been mere wishful thinking on Crowley's part. "It is," a pause, "horrific, yes, but there are many humans living healthy lives elsewhere. This will stop spreading and go away, eventually. The world is only on its fifth millennia, after all." Aziraphale straightened up, drawing in on himself in that way that set Crowley's teeth on edge. "It can't end now. It is Written."
Crowley took no comfort in Aziraphale's faith. Faith was the one part of Aziraphale Crowley had never learnt to embrace. He kept to himself after that conversation, letting terrible humans do far worse work than he ever could think up, accepting credit for it while he mastered the art of sleeping and wished Aziraphale and him could be given tasks anywhere but in this cursed part of Creation that one day would be called Europe.
Thankfully that dreadful century only lasted a hundred years, as was the custom of centuries. The Black Death went away, even if the many new weapons stayed and the Hundred Year War kept up momentum. The 15th century came rushing in and Crowley had never welcomed the passage of time more.
He ran into Aziraphale in the Ottoman Empire in 1402 and immediately began his next nest. Several followed it.  He made sure Aziraphale never saw them. Not yet, not yet.
No nest he built felt quite complete. No matter how many rooms it had, how comfortable its sleeping area or how brightly lit or cosily dark, no matter where he hid his feathers, it never felt fit to present to anyone. Least of all Aziraphale.
Ironically, a conversation with Aziraphale gave Crowley his next idea to try in his trial and error nest building.
"I couldn't resist," Aziraphale had said as he showed Crowley the stack of books. He'd been carrying them with such care, showing off strength one could go forgetting he possessed even when one had known him since the Garden. 
At this point in time, Crowley had learnt to gauge when Aziraphale was presenting him with a passing fancy and when he was sharing something fragile and important. The written word had captivated Aziraphale since its invention, and Crowley well remembered the near disaster that had been the burning of Alexandria's library.  While they did often squabble over minor things (and on rare occasions ended up in arguments that took years to cool down) Crowley had no intention of starting one now.
"Smart thing, storing up on those." He'd indicated the books with as casual a nod as he could manage. "Better and better quality, from what I've seen. You learning to make them?"
The delight that this idea clearly fuelled in Aziraphale lit a growing warmth in Crowley, burning brighter and brighter at Aziraphale's hesitant, "Do you think I should?"
"Got to be a good thing, doesn't it? Helping to store knowledge. That's got to be one of your things." In this Crowley had no doubt. Aziraphale had his (gloriously) selfish impulses, but keeping books could hardly count as any degree of evil. Someone probably thought it was, but humans made up new sins every other century and then threw them away again, as often as they switched up their body language and thoughts on privacy. 
"I suppose you're right," Aziraphale had said, beaming. Crowley had mentally begun adding bookshelves to his nest.
Meaningful trinkets were clearly what he'd been missing, and space for them. Crowley himself kept memorabilia more than items he valued for their function, but he'd been keeping said items stored in all manner of places, safe and out of sight. Gathering them all in one place set his heart racing, but once he'd gotten Leonardo's portraits and that fan Aziraphale had forgotten after sharing tea during the Tang dynasty up on the nest's wall, the place took on a more acceptable, inviting air.
This was what he'd been missing. Other than the obvious.
Surprisingly, for all of his reservations about being discovered by Heaven or Hell or both, come the 18th century Aziraphale began inviting Crowley back to whatever dwelling was his for the moment, mirroring what Crowley had done before the Mudslide Disaster. Dinners in taverns soon became quiet evenings sharing a meal in the home Aziraphale had established in the city or town or village they'd ended up in that decade.
Crowley tried to not see this as any kind of sign. He still took it as one, nursed the hope it gave him far into the night as he filled yet another house with black feathers, moved precious memories from old nest to new.
"Do you have a home?" Aziraphale asked Crowley one evening in 1731, during a dinner shared after a successful stint at cooperation.
"A what?" Crowley's mouth answered before his mind could catch up with the question.
"A house," Aziraphale clarified, gesturing at the ceiling and walls that surrounded them. "You've had them before. I've seen them." They had indulged in a fair share of alcohol during the meal, and after it. "It's been a while since I saw you in," he hiccoughed, "in one. Centuries I think. Several centuries, in fact. Have you got one?"
Crowley poured wine into his windpipe and willed it back into his mug before he could start coughing up a lung. "Bwhuk?"
"Oh don't you give me that look," Aziraphale said, clearly affronted. "We're currently in my home. Why do you feel the need to keep your base of operations hidden when we meet in mine all the time?" His gaze didn't focus but he still managed to deliver an impressive glare mixed with worry in Crowley's general direction. "Are you-"
Crowley, locking a mounting wave of panic behind all personal defences he could muster, tried very hard not to think of the piles of feathers taking up the floor space of his current nest. No matter if they meant nothing to anyone but Crowley, no matter if he longed to find out if they would mean something to Aziraphale, instinct screamed at him that he couldn't show the nest. Not yet. It wasn't finished! It was a mess!
But he also couldn't have Aziraphale start questioning him again. "No, no, we can meet at my place next time," he mumbled into his jug of wine, letting it cover what parts of his face his glasses didn't. "Just didn't cross my mind. Don't think you'll like mine. Y-yours is, uh, more…more home-y. Cosier."
"Do you think so?" Aziraphale said, beaming in a way that stopped Crowley's heart in the best of ways. "I do try. You know," he leaned forward in his chair, teetering on falling off it, "I've been thinking of opening a bookshop."
He whispered the words as if they were a great secret, like he'd once whispered how much he enjoyed the theatre, or the first time he'd shown Crowley his first favourite pair of shoes. Like someone sharing something beloved and wonderful, yet shameful.
The bookshop plan came as no surprise in itself. A bookshop seemed a fine solution for where to keep all the books Aziraphale had amassed without calling Heaven's attention to an angel holding on to so many worldly possessions. It also sounded far more permanent than any home Aziraphale had ever made before.
Crowley forced himself not to react too much. That would put far too many cards on the table. "A bookshop sounds like a fine idea," he said, allowing himself a genuine smile, encouraging, tempting.
"I thought so," Aziraphale said, wiggling in that way he did when he thought he'd done something clever. "They can't complain if I'm doing my best to fit in, can they?"
"No they can't." Crowley smiled and smiled. "More wine?"
That evening, Crowley went and constructed his first ever decoy nest. It wasn't a nest, not really, but it was a base of operations to invite Aziraphale to. It was sterile and unfriendly, and they quickly returned to their custom of meeting at Aziraphale's home. Crowley kept up the decoys, just in case.
Their work led them apart a while after that, but not for long. Crowley couldn't stay away when Aziraphale got himself in more trouble than he could handle, almost ending up decapitated during the French Revolution. Sometimes Crowley thought Aziraphale got himself into danger deliberately. A foolish thought. A wistful thought. Crowley had no idea how Aziraphale had managed to keep from discorporating this long. If not for his demonic intervention, the angel would have ended up back in Heaven millennia ago!
Each of these brushes with near-body-less-ness chilled Crowley to the bone, though the thrill of getting to come to the rescue never wore off. He pushed all that aside as they went for lunch, had crepes, laughed and shared stories of their months apart. He did his best not to react too strongly to Aziraphale confirming that the bookshop idea was well under way.
Ever so slowly, they circled closer to each other. When they before had skipped from continent to continent, country to country, they now both settled down in what had become Great Britain.
Well, Aziraphale settled down there and Crowley swiftly followed.
His emotions ran away with him when Aziraphale finally opened his bookshop in 1800. With the brief threat of promotion (Aziraphale's) averted (by Crowley) a sense of relief and hope dug its claws into Crowley and refused to let go. He paid the angel visits every other week, thinking up excuse upon excuse to not only take Aziraphale out to dinner or music halls, but to visit the bookshop.
He might have been looking for feathers.
"What did you say it was called?" Crowley shouted to Aziraphale one day in 1802 when the angel had gone to the back of the shop, having remembered mid drinking session that he had a project there only half finished. This had left Crowley alone in the main portion of the shop, unobserved.
"I'm not sure what it's called now, if it's still there, but when it opened Antoine called it La Grande Taverne de Londres," came Aziraphale's answer from deep within the shop. He'd clearly sobered up, likely not wanting to risk mucking up a book restoration.
Crowley had sobered up too, to better sneak about. "And when did it open?" he kept up the conversation, making sure his voice carried from the sofa in the middle of the room where he'd been seated, instead of from where he actually stood.
"1786?" came Aziraphale's distracted reply. "Or maybe 1782? I honestly can't recall. The food was masterfully prepared, either way. I highly recommend it!"
Crowley found no feathers, but plenty of inspiration for his next attempt at a nest.
Buying a whole estate had been ludicrous and yet the only logical next step. Aziraphale looked so at home in 19th century London that the idea of him in a grand estate near the city fit perfectly into the world. A large house for the two of them meant there'd be plenty of space for books and beloved trinkets as well as a number of places to keep feathers out of sight.
Things were going well. Wonderfully well. They met up almost weekly, and Aziraphale seemed settled like never before in London and in his bookshop. Being a schemer by nature, this triggered Crowley's mind to immediately jump to step five and six of his current plan, though he technically still should be working on step one. Step one of course entailed finishing the nest. Step two was showing Aziraphale the nest. Step three and four were still a work in progress, far too dependent on Aziraphale's reaction to said nest, which Crowley had no control over. But step five and six he could control.
He'd been so sure Aziraphale would give him the holy water. It hadn't even crossed his mind that the angel would think he might use it on himself! Before he knew it, he was metaphorically back in the second century, standing next to an equally metaphorical mudslide and buried tent. Only this time, he couldn't make himself go begging the angel for forgiveness. Fraternising?! Was that really all their Arrangement was to Aziraphale?
It hurt. More than Crowley thought it could have, it dug deep into him and gnawed and bit and clawed, icy and paralysing.
Crowley ended up spending the latter half of the 19th century in bed, waking up at the dawn of the 20th with a commendation for a number of nasty things the humans had gotten up to during his attempt at rest. He even got a word or two of praise for his mastery of stealth.
The nest…well, he didn't destroy that one. He didn't sleep away the century in it either. He had it sold, all his personal affects carefully stored in a handful of safe places right before he faked his human persona's death and let a barrister take over. Then he found a quiet village in Scotland, made himself the owner of a house on its outskirts, and covered himself with all the blankets he could find.
The feathers he hadn't kept. They burned, as always.
When war came back to Great Britain, Crowley finally got out of bed. He didn't much involve himself in the first one, but by the second he'd distracted himself living as a human for so long he couldn't ignore the fighting. Not completely.
Also, Aziraphale almost got himself shot by Nazis. Hurtful words or not, there was no way Crowley would let that happen. Even if it meant walking into a church.
"Would you," Aziraphale had said, car door already open and book bag safely cradled to his chest. "Would you like to come in? For tea?"
Crowley had been oh so tempted. But Aziraphale sat tense in his seat, avoiding eye contact. Maybe it was panic in hindsight at how close he'd come to being discorporated. Maybe.
But their fight in 1862 still nagged at Crowley. Hell, it had left him out of commission for fifty years. He couldn't risk setting off something like that, not so soon. He wondered if he ever would dare risk it again.
"Some other time, angel," he'd said, forcing his hands to relax on the Bentley's steering wheel. "Busy days for us demons, right now. See you around."
He'd driven away. He hadn't looked back. He hadn't been able to work up the courage.
The latest and most long-lasting nest, Crowley began in 1971. Since he'd sworn off ever building another one, its fortitude was more than a little ironic.
Its foundation was laid in 1967. He'd gotten back to his place of residence, a tartan thermos full of holy water in his trembling hands, and the urge had hit him like a runaway train. He'd begun shedding feathers right there on the floor, wings peeking into existence without as much as a by your leave.
It had always been an urge. He wouldn't have started doing something so foolish as building nests if the act hadn't been a compulsion,  but this time it wasn't so much a nagging thought as it was a need.
"Fuck you," he whispered to no one in particular. He got to work securing the holy water and then he had a lie-down. He tried to go to sleep, but Aziraphale's parting words played on repeat no matter how he tried to force them away.
How could the bastard give him hope and tell him they needed to slow down, all in one meeting?! Their conversation could have been interpreted many ways, but Crowley knew Aziraphale better than anyone else in Creation. He knew he hadn't been let down easy or told in some roundabout, gentle way to keep away for good. Just to wait. Crowley could have blamed this chosen interpretation on wishful thinking. He could have, but that would have been lying and he didn't have time for lying or denial any more, not when it came to Aziraphale. The angel had that covered for the both of them.
Crowley drifted in a no man's land between glorious anticipation and pure dread.
"A picnic!" he yelled at the bleak ceiling of his flat - not a decoy nest, seeing as he had no nest to hide then. Decoys required he try to match them to his corporation's current style and he hadn't had the energy for that since 1862. "Dinner at the Ritz!"
They'd had food together plenty of times. They'd even shared food while sitting on the ground, long before tables or table manners. But the rules for food sharing were ever changing. Surely Aziraphale must have known how suggestive his propositions came across? His style of clothing may lag behind the times but the angel had always been a stickler for keeping up with proper conduct.
"He can't have meant it like that," Crowley told himself as he lay on his bed in a pool of feathers. The extreme moulting would have left a bird's wings bare to the bone, but on Crowley the damned feathers grew back as quickly as they fell. He grabbed a handful of them, crushing them as he gritted his teeth, fighting a losing battle against long entombed daydreams. "I'm just making mountains out of… Out of… damn, what's the word?"
The metaphor escaped him. In frustration he flung the ball of feathers away from himself. They fluttered to the floor, infuriatingly soft and light.
"I can't make another one," he said, sounding exhausted even to his own ears. "I can't."
He lost track of time. The moulting had stopped, but his mind wouldn't stop spinning in circles. He thought of his caches, of all the things he'd never been able to throw away completely. He thought of Aziraphale's bookshop, still in the same place more than 150 years from its opening day. The longest time the angel had stayed in one place, one home.
Eventually, he got up and went to work. His actual work. He threw himself into city planning, into TV schedules and advertisement; things that would keep him well away from anything angelic or heavenly.
These distractions lasted him four years. Then, while driving back to London from a week long job out south-east, he came across The Cottage.
The Cottage was located in A Village, because actually remembering their real names felt like an invitation to failure. The Cottage - which Crowley eventually managed to think of as merely the cottage, without the ominous capitalisation - caught his eye with such force that he nearly put the Bentley through a tree.
It was perfect. Everything inside of him screamed that it was perfect; location, size, style, garden. All of it.
"Someone lives there," he said to no one, staring straight ahead out the windscreen, refusing to turn his head and look at where the cottage loomed. No, not loomed. It looked far too welcoming and homey to loom, which made the situation worse. His mind flooded with images of comfy sofas and bookshelves and blooming flowers. "Or its full of vermin. Or the neighbours are Nazis."
He got out of the car, cursing and trailing feathers behind him.
The purchase ended up an easy affair. The cottage had been for sale for a whole year with no takers, or at least no takers the current owner had been interested in selling to. The second it became clear that Crowley had no intention of tearing the cottage down to build something else, he could sign for it that same day.
He could always sell it. Would be a suitably evil deed, buying a quaint cottage under false pretences and then giving it to some rich businessman in need of a second golf course.
"Everything go well?" Aziraphale asked him as they met up in St James's Park two days later.
"Yeah, it went all right." Crowley threw bread at the ducks, hitting one in the head. "Yours?"
"Quite well." Aziraphale had been out of town as well, blessing a peace negotiation a few countries over. "Is there anything we need to-?"
"No." Crowley had been prepared for the question. He'd focused so hard on answering it in an uncaring and relaxed way that he'd forgotten to wait for Aziraphale to finish speaking. Biting back a curse, he added, "No, we're good. You did your thing, I did mine. Head offices happy and so on." He made sure to keep his eyes on the ducks, glaring them into submission. 
Aziraphale shifted his weight from foot to foot. Crowley couldn't see it, but he didn't need to rely on sight to notice.
"Would you," Aziraphale said, hesitant in that way he only was when he planned on suggesting something he felt he shouldn't. Crowley kept very, very still. "Would you care for a drink? I've, eh, got my hands on a new vintage of red I thought we could try."
"At the bookshop?"
"Yes." More hesitation, along with the wringing of hands. "And I thought we might," hands fluttered to the side, mirroring the way he'd likely shift his wings if they'd been visible. "Well, it's a little silly, and I know you don't enjoy tragedies, but I've ended up with quite good seats to a production of Hamlet that looks promising, and-"
"Sure," Crowley said, this time intentionally interrupting, to keep Aziraphale from working himself up and talking himself out of his own idea. As fun as it could be to see him flustered, it wasn't as enjoyable to watch when your own unnecessary heart was about to burst out of your chest. "Theatre and wine, I'm up for that. When is it?"
Aziraphale drew in a breath, a soft little huff of air that signalled pleased surprise. "Tonight, at seven."
Crowley dared glance at Aziraphale then. Their eyes didn't meet, Aziraphale's gaze focused on the squabbling ducks in front of them, which gave Crowley the opportunity to take in the angel's utter joy without worrying too much about his own expression.
Humans had this notion that angels were beings of light and love, and Crowley couldn't really fault them for that - humans rarely met any angels. In practice, most of them approached their God given tasks as the work it was, with varying degrees of enthusiasm, and they rarely did more than reflect light.
Not Aziraphale, though. No, Aziraphale could be petty and selfish and vindictive, but he was also kind in a way so unlike all other angels Crowley had ever met and when he smiled, truly smiled, he shone.
Or it just looked that way to Crowley. Because, as implied previously, Crowley was fucked.
Pretending to have lost track of the time, though really doing his best to hide how Aziraphale's joy utterly delighted him, Crowley looked at his watch. "Gives us an hour to get there. Lift?"
Aziraphale turned towards him, still shining. "That would be lovely."
It was in that moment Crowley knew he wouldn't be selling The Cottage.
The rest of the 1970s he spent ferreting out his caches and moving suitable pieces from them to the new nest, between work and spending time with Aziraphale. He also went back to his old habit of decoying, just in case. The flat he stayed in changed bit by bit, decor and location following the changes of his corporation as fashion demanded.
The 1980s and 90s he arranged the rooms in the cottage to perfection. He made sure that the locals remembered workmen heading over there every now and then, on the off chance that a nosey neighbour should glance inside and notice all the changes. There were other ways to prevent such things, sure, but this was a nest, not a scheme or a decoy. It needed to be solid, or as solid as he could make it while working via demonic miracles.
He even employed a cleaning company to tend to the place yearly. They'd always call ahead to make sure he still required their services, and while he'd say yes he'd make sure to clean the whole cottage himself. He left the cleaning company with both payment and the memory of having cleaned the place, so they wouldn't ask questions. Wouldn't do to let them grow tired of him and stop reminding him to give the nest a thorough cleaning.
The 21st century rolled around and that pinged something at the back of Crowley's mind, but he was too busy putting the finishing touches on the nest's library and fretting over where to best hide his feathers to pay it much mind.
Until he was handed the Antichrist.
Now, one would think the cottage would slip Crowley's mind while he and Aziraphale worked to prevent the oncoming end of days. Strangely, rather the opposite happened. When faced with the stark reality that the war to end all wars could be but eleven years away, the cottage turned into a soothing escape. What time he didn't spend as a nanny or meeting with Aziraphale, Crowley dedicated to planning. He didn't go to the cottage too often, paranoid it would come to harm, but he kept sketching on ideas for it, for the same reason humans look at cats videos while dealing with grief or burnout or both.
He even brought a handful of memorabilia into his decoy nest; a breach of his own strict protocols that he indulged in to steady himself.
"I can't believe it'll all be gone soon." They'd been meeting in a cafe at the British Museum, Armageddon only four years away. "U-unless we succeed. Which we will. Of course."
Crowley, who hadn't slept for three months and who sat before his first bite of food in two weeks, didn't have the energy to summon false courage. The world around them had a heavy quality to it, the air itself counting down to the greatest turf war in history.
Aziraphale kept speaking, as he tended to do when nervous. Where nerves silenced Crowley, they gave Aziraphale the ability to talk himself in circles and loops worthy of a race car track. "There is so much I still want to do," he said to his devilled eggs. "Places to visit, plays to see, books to read. New favourite authors to meet! New mad inventions to observe, waiting to see what ends up used and what goes away for a while only to be reinvented or rediscovered." He turned a shaky smile on Crowley. "I don't think humans ever will stop surprising me. Isn't that delightful?"
Crowley managed a curt sound of agreement, most of his attention on suppressing the urge to say, "I could surprise you too. I bet you've never seen a nest built by a demon before." His angel food cake remained untouched.
"Do you think they'll ever figure out the joke about the dinosaurs?" Aziraphale asked, coaxing Crowley into conversation. Crowley let himself be coaxed, let Aziraphale talked the both of them away from worry, regret and anxiety, if only for an hour or two.
Time ticked down to an ending and the both of them did their best to alternate between ignoring it and thinking up new strategies for how to prevent it, how to keep Warlock as neutral and human as possible.
Direct intervention with the Antichrist came to an end on the boy's 8th birthday, on orders from Hell. This left Crowley far too much free time in which to fret. Once he'd cleaned his decoy nest to perfection and started all the unnecessary roadwork he could think up, he gave in and visited the nest.
You'd think there wasn't much left to work on there, given that Crowley had been tending to it for more than forty years. You'd think, but Crowley was a perfectionist and an immortal, which could be a heady combination when it came to interior design. He also hadn't figured out where to store his feathers. He couldn't leave them in the bedroom forever, no matter how soft an addition they were to the bed. Even stuffed in a mattress and pillows they were too obvious, too eye-catching.
In frustration, he took a break and poured all his energy into the garden. Far too soon he had it blooming and thriving and trembling, robbing him of distraction.
This is when he turned his attention on the village. Asking Aziraphale to leave London would be ludicrous all in itself, of course, a pipe dream! But Crowley couldn't even in his most fanciful of daydreams imagine asking Aziraphale to come live in a community with half its houses empty. Through all of their shared history, Aziraphale had always been drawn to bustling centres of culture. It seemed to Crowley that Aziraphale wished to be where the newest plays were being written, where the best food could be found, where he'd never have to feel isolated.
Admittedly, distance didn't much matter to immortal creatures made of pure magic, but it was the principle of the thing. The village needed to thrive.
"Online sales, you say?" said Grace (oh the irony) to Crowley as he'd finished giving his temptation performance. She owned the local bakery, a vital corner stone in his plan to make the village fitting as a (very very hypothetical) long term home for Aziraphale. "Huh, hadn't thought to try that, but I sure could do with a bit of extra income. Very kind of you to assist! Inherited the old cottage from your uncle, you said?"
Next came the local bookshop, the community centre, the gardening club and the combined library and cafe. Crowley made sure his interference remained distantly demonic, redirecting money from bank accounts and stealing prize nominations for the benefit of the village while making sure his actions showed up as random acts of mayhem Down Below. He made doubly sure that his actions attracted no human attention. The last thing he needed was for law enforcement to come snooping around the village.
Before he knew it, there was less than a year left until he'd find out if his and Aziraphale's plan with the Antichrist had worked out. The realisation hit Crowley like a ton of blessed bricks.
"Where have you been hiding yourself, dearie?" Old Margret - thusly nicknamed to distinguish her from Young Margret who'd moved back from Sussex the year before- asked in early 2019 when Crowley hadn't shown his face in the village for a good six months. He'd been out in the garden, taking his stress out on the new rose bushes, and hadn't noticed her sneaking up on him. Crafty old woman.
"London," he answered, doing his best to keep his body breathing evenly. 
"Throwing yourself into work again?" Old Margret had parked herself on the other side of the garden wall, clearly no leaving any time soon.
"You could say that."
Old Margret tutted at him. "I thought you were a sensible young person who understood that work isn't the end all be all of life."
Crowley, being one of the farthest things from a young person that existed on Earth, chose not to comment. He instead silently cursed his own stupid idea of getting 'established' in this stupid village, which was clearly going to burn with the rest of everything worthwhile unless he and Aziraphale managed to pull off their plan. No pressure.
"Magpies having a go at your strawberries?" asked Old Margret, derailing Crowley' mounting panic. He followed her gaze and was gut-punched by shame. Dozens of black feathers littered the grass between the rose bushes and the wild strawberries he'd blackmailed into the garden the year before, out there for all the world to see. He hadn't even noticed he'd been moulting. His wings hadn't even manifested!
Then he saw a white feather and nearly discorporated before Old Margret's words caught up with him. They weren't his feathers. They weren't…anyone's feathers. Just bird feathers, regular feathers, not, not indecent feathers.
Running away from the word 'indecent' at the speed of light, his mind focused itself on the strawberries with a will. They'd clearly fought back against the thieving magpies, as ordered, but he could see a few missing berries. It seemed he'd have to give those lazy plants another talking to. Those strawberries weren't for birds, they were for-
"If you've got the time, would you mind gathering some to bring to the community centre tomorrow evening, luv? Fatima is starting up a new arts and crafts circle, and this time the theme is feathers."
That brought Crowley's attention back around. "Huh?"
"Arts and crafts," Old Margret repeated, smile wide and far too innocent for such a cunning lady. "Starts at six o'clock. We'd be ever so grateful for all contributions. Ta-ta!"
Crowley watched her go in numb shock, gathering his thoughts together like a parched man careful not to spill water from his cupped hands. It wasn't the subtle invitation to join the arts and crafts evening that had him reeling; neighbours of the cottage had tried to get him involved in communal activities since he'd first interfered with Grace's bakery in 2017.  No, it was the disturbing yearning the idea of feather decorations had started up inside of him.
The concept wasn't new to Crowley. Humans had made decorations out of all parts of Creation since Adam and Eve had left Eden. They'd make art out of trash if given the chance, which was one of the many things Crowley liked about them. Feathers had been one of the first things to adorn human-made jewellery and weapons equally.
So why hadn't the thought ever struck him before to…to do something similar with the near mountain of moulted feathers hidden in the cottage's bedroom?
The way his face more or less caught on fire as he allowed this thought to fully form answered that question.
Crowley told himself he wouldn't. He told himself this all the way to the community centre, where he showed up the following evening with a box of magpie feathers. He told himself this as he sat through Fatima's tutorial on how to sanitise the feathers, side by side with Old Margret and ten other villagers. He mentally screamed this at himself as he got back to the cottage after midnight, tipsy and trembling, and took the stairs one careful step at the time up to the nest's one bedroom.
He attended every damn meeting of the arts and crafts group that spring. 
All went smoothly until the group's fourth meeting. Since the majority of the people attending had young children, no one switched their phones off during class. It wasn't unusual for the lessons to be briefly interrupted by a harried partner or babysitter calling for back-up or advice, so no one raised an eyebrow whenever a jaunty tune or old fashioned ring broke through the usual chatter.
Thus, while dealing with a really finicky bit on a feather and flower decoration, not even Crowley fully registered that his phone had started ringing.
On pure reflex, he picked up and said, "Can't talk right now, in the middle of something."
"Oh, dear, sorry to bother you. I-I just wanted to know if we could reschedule the opera tomorrow? There's this auction-"
Attention mostly on not breaking his flower arrangement, Crowley interrupted with, "Yeah, that's fine. You go have fun book hunting. Tuesday instead?"
"Ah yes, that would be lovely! I'll see to tickets. Thank you for understanding."
"I've known you long enough to not get between you and books, angel. See you Tuesday." He hung up, smiling at Aziraphale's ridiculous "Toodeloo then!" as well as at the knowledge that Aziraphale would be in an extra good mood come Tuesday, should all go well at the auction. Or maybe it'd go terribly and he'd be deeply frustrated. Either way it'd mean a long conversation, longer than average, and maybe they'd end up drinking the night away in Aziraphale's shop after the opera. Maybe he'd even pretend to pass out drunk on the bookshop's old sofa, spend the night. Or morning. Yeah, that was an excellent thought.
Crowley gave a triumphant "Ah-ha!" as he managed to attach the final feather to his project. He looked up to find the rest of the group, even Fatima, staring at him with great interest. Crowley immediately backtracked through what he'd just said, out loud, in front everyone. Also, the fact that he'd managed to put Aziraphale on speaker caught up with him. Because the universe was like that sometimes.
Pretty often, actually, in Crowley's experience.
"Angel, huh?" said Mitch with a canary-catching grin. "Cute pet name."
Crowley scrambled for words. "It's just a nickname. He's terribly pious. Insufferably so."
Whether it was his words or the way he'd said them  the gleeful expressions around him swiftly turned to looks of either confusion or sympathy. Somehow that was worse. Crowley quickly excused himself.
The likely discussed him and the phone call while he wasn't around , but they mercifully avoided mentioning it to him. The lessons carried on through fireplace decor, window chimes, frames, and lamps.
The Antichrist's 11th birthday ticked ever closer.
"Fatima, do you think we could do something like this next time?" Andrea asked near the end of spring, holding her phone up to show off whatever Pintrest fuelled idea had grabbed her attention this time. Crowley had lost count of the times the class had been derailed by her flights of fancy, but since they kept extending the lessons no one complained.
"Yeah, I could work with that," Fatima answered. "Why don't you show your idea around while I go see over my supplies?"
Andrea passed her phone on, the tiny machine wandering from hand to hand, accompanied by sounds that varied from mild interest to "ohs" and "ahs". When it reached Crowley he nearly dropped it.
The screen showed off two round mirrors, each with a halo of feathers around it. One ring of feathers was black. The other was white.
Somehow, he managed to keep it together through the rest of the lesson.
At least, he thought he'd managed to, until Fatima called an end to class and Old Margret pulled him aside before he could up and leave. He stopped because she'd been on him earlier about some village event or other and that would have been a welcome distraction. However, what she said was:
"He likes white, does he?"
"Your young man."
Crowley made a noise caught between pain and relief. The question broke him a little, but it was so freeing to have someone see. Even if it wasn't the right someone.
Humans had mistaken him and Aziraphale for a romantic couple innumerable times. While such misunderstandings usually pleased Crowley they were based on human habits and cultures, and those were ever changing. The nests and the feathers, however, they were constant, permanent. They couldn't be laughed off as a misunderstanding or blamed on the ever changing whims of humans. Old Margret likely had no idea what she'd wandered into, but that didn't matter.
"Yeah," Crowley said to the painting over Old Margret's shoulder. "It's sorta his colour."
"He's in London?"
"Thinking about moving any time soon?"
"N-not that I know."
Crowley outright flinched when Old Margret took one of his hands. He didn't pull away though.
"I get the impression that you've been waiting for this fellow for quite some time now, dearie." She patted the back of his hand as she spoke.
Crowley allowed himself a huff of laughter, because there were exaggerations and then there were exaggerations. "You could say that."
"Then maybe it's time to stop waiting." She looked up at him without pity but with deep sympathy, a look very hard to pull off. Had he not been the target of it, Crowley would have complimented her skill. "My George is a wonderful man and I'm ever so happy I married him." She gave Crowley's hand a gentle squeeze. "I'd never have met him if I'd clung too hard to loves before him. Just a thing to consider."
Crowley shook his head. The mere thought of someone who wasn't Aziraphale walking into his nest - human, angel, demon, or otherwise - turned his stomach. For fuck's sake, he wasn't making nests because he wanted a hypothetical someone to wander into them! He was building them for Aziraphale and Aziraphale only and there was no changing that. If he hadn't learnt to live with that yet it was about damned time he did.
"I see," Old Margret said, as if she actually did.  With a soft sigh, she let go of his hand and smiled. "Don't you go pining away on us, luv. We still need you to help out with promoting next month's flea market."
Muttering the words 'slave driver' without much force, Crowley made his retreat.
He spent that night in the nest. He got very drunk and very maudlin, toasting each and every piece of memory and newly made decoration like human soldiers would toast each other before battle. He then locked up and left, likely forever.
The summer of 2019, Crowley didn't visit the cottage. There wasn't time. There literally was a finite amount of Time left for Earth and all the creatures on it. Unless he and Aziraphale managed the impossible.
The Antichrist turned 11. Hell hounds were released. The Four rode. Angels and demons armed themselves to the teeth and stood ready, howling for blood.
And then…well, then the world didn't end.
Crowley had been sent to Rome to tempt Emperor Caligula and he'd gotten their just in time to witness the final heydays, so to speak. The assassination of Caligula and Caligula's immediate family had been equally disturbing to take in. All in all, the only reason Crowley put up with Rome was because it had interesting company in it. He never did figure out why Emperor Claudius took a shine to him.
The servants had quickly found other work. The slaves had quickly found themselves in completely different countries with new names and plenty of fitting currency. Crowley argued that as slavery was part of Rome's social structure, all actions against society automatically were evil - especially as all money given to the slaves had been stolen. Stealing from the rich was extremely evil, since you could do it so many more times than you could steal from a poor person. That was just common sense.
Seeing as the angels' shapes had been God's first project that involved corporeal forms, there had been some trial and error involved. Well, trial and error on the angels' part. They'd all been given the ability to both take a visible form and change their shape, and then just been told to find a form they felt suited them. Many a burning mass of wheels and six-headed lumbering giants populated what would become Heaven for an amount of existence (that couldn't really be called 'a while' since there were no minutes or hours or days yet), ever changing as this or that angel found out news about yet another work-in-progress the Lord had on Her metaphorical table. It wasn't until humans were revealed to be God's favourite project that the majority of the angels took on humanoid shapes, either to please God or due to the newly invented concept of peer pressure. A handful of the Heavenly Host staid non-humanoid, but most settled for the general humans-with-wings form and have stayed that way ever since. Fallen angels aka demons are more prone to shape-shifting, but like angels they are creatures of habit. Thus their chosen default shapes also tend towards the humanoid.
It was a rather complicated plan that had involved cutting two warring groups of humans off from each other, thus making their chieftains no longer interesting in the eyes of Heaven and Hell. Sadly, this, as so many of his plans, blew up in Crowley's face rather spectacularly while accidentally keeping him in Hell's favour. It had been Crowley's first tentative attempt at cooperating with Aziraphale. It had also been the last time he'd ever attempt cooperating without any actual established cooperation beforehand.
Crowley was. Obviously.
Having lived on Earth for 6000+ years, Crowley's many failed nests could have filled a number of scrolls or hard drives or whatever manner of information storage one operated with. A detailed list of them would slow any story they showed up in down to a grinding halt, so they're best left vague and summarised.
Crowley had stayed away from the Garden once his first temptation had been over and done with, sticking to the desert outside. While he'd been meant to keep an eye on the humans, he'd mostly paid attention to the angel closing up the hole in the Wall with impressive speed. It had been distracting in a way Crowley couldn't put words to then.
If asked, Aziraphale would definitely have described this event as a full on disaster, nothing near about it. Then again, he'd been busy watching knowledge burn while Crowley's focus had been on getting the two of them out of the fire with their bodies intact and operational.
The Seven Cardinal Sins irked Crowley most of all. Some monk in the fourth century, millennia after the creation of Creation, sits down and writes a list about things he thinks are Bad, and suddenly several humans decide he's got something figured out and start following that list. It had taken Crowley decades to convince Aziraphale to enjoy food again! Dante Alighieri's blasted poetry hadn't improved that in the least. Another terrible thing spawned by the 14th century.
At least that's what Crowley told himself.
This of course didn't work. The ducks of St James's Park have stopped fearing death many years ago, and stopped fearing Death somewhere in the 1920s. Crowley ranked very low on the list of threats against duck-kind.
Crowley tended to forget the whole breathing thing when he got stressed out, only using his lungs when he felt like shouting or screaming. Understandably, this tended to disturb humans and didn't make for good neighbourly relations. Trembling rose bushes the human brain could filter out or blame on a very local gust of wind, but people who didn't breathe pinged all of their I Saw This In A Horror Movie Once gut reactions.
While not the only interesting thing to ever arrive in this village, a vintage Bentley driving man's supposed inheritance of an up-until-then empty though cared for cottage, that he then proceeded to clearly pour his heart and soul into maintaining but not living in, did draw the attention of the locals. Grace, having been the first person to actually speak to Mr Anthony J Crowley swiftly had the local gossips - Old Margret, Andrea, Mitchell aka Mitch, and Jane - invested in the mystery of this business savvy man of indeterminate age (Grace had put him somewhere between mid thirties to early forties, while other observers put him anywhere between early twenties to mid fifties. Crowley's shape-shifting tended to get out of hand when he was stressed). They quickly set to work figuring out who Mr Crowley really was and what his plans for the cottage were. A handful of scattered over-the-garden-wall conversations and gentle ambushes at the bakery later, they all agreed that Mr Crowley - Anthony at that point - was 1) invested in the village's prosperity and 2) clearly working out some issues through house renovations. Said issues were what they set their sights on unravelling next, which at the start of 2019 still remained a work in progress.
Much to the delight of the arts and crafts group. While Anthony Crowley proved impressively evasive in talking about himself, he could keep conversation going all night and took the lessons seriously, keeping the group on task despite Mitch and Andrea's tendency to blather on about their children or that new show on telly and not hear Fatima calling for the group's attention.
It was both.
Yes. At length. Wine was often involved.
She did. Old Margret had seen people hopelessly in love before, sometimes in her own mirror. She knew what a person ready to let go looked like and such a person looked nothing like Anthony J Crowley.