In the Beginning, there is sunlight.

Aziraphale hefts the sword's weight in his hand and watches the flames flicker, the air around them shivering as if it were painted on a stream of water.

On impulse, he raises his other hand to the blade, fingertips plunging into the blue-white brilliance of it until he can feel the smoothness of the metal.

It doesn't burn him.

"That's a pretty neat trick," the Serpent says appreciatively, watching him from the grass. "Want to see one of mine?"

Aziraphale has still not discovered a sufficiently polite way to say 'begone, foul demon', so he nods.
The Serpent grins at him more widely than usual and curls up on the ground, biting into the end of his own tail.

"Er, yes. Very nice," Aziraphale says uncertainly. "What does it mean, though?"

The Serpent shrugs lazily, coils rolling. "Beats me. It sure looks interesting, though, doesn't it?"
They both watch as the two naked forms of the humans make their way over a stream, not far from the Gate.

"Be right back," the Serpent says thoughtfully and slithers off into the foliage.

Aziraphale sighs and sits down, idly counting the blades of grass.

It takes a while for the demon to show up again, and when he does, he seems nervous and eager to distract them both with new tricks, contorting himself into shapes and having the angel guess what they are.

Much, much later, as they huddle together under a growing thundercloud, Aziraphale wonders, in the privacy of his mind, if he should have used the sword for a different purpose while he had it.

It doesn't take him long to decide against it, and that is only a mild surprise.

Things turn a lot less simple, he discovers, with more humans in the mix.

"You really want to do it this way?" Crawly mutters faintly, eyeing the tip of the spear levelled at him with obvious distaste. The bonfire of a village burns in the distance, an insistent reminder.

"I'm sorry," Aziraphale says truthfully, "I really cannot have you interfering with these things again. You understand, I'm sure. You have your job, I have mine."

Crawly scoffs and nods, looking oddly disappointed as he turns abruptly, scales hissing against the grass that hides him from sight.

Hours later, when Aziraphale feels a sharp stinging in his ankle and the nauseating pull of limbs suddenly grown unyieldy, he reckons he should have seen this coming.

There is a certain back-and-forth to it; century in, century out. Aziraphale will spot a wile and thwart it, and Crawly – Crowley – might see an instance of do-goodery and sow salt in it - sometimes literally.

(The incident of the miraculously transformed sugar during one of the more politically important wedding feasts is best left undiscussed.)

Sometimes Aziraphale looks at him and sees the demon that, when you got down to it, taught humans how to sin.

And sometimes he remembers the snake that wanted to show him a trick.

Either way, they end up fighting more often than not. It takes Aziraphale centuries to admit that it is starting to grow old, and millennia more to actually do something about it.

Three days before the Library of Alexandria burns down, Aziraphale spots Crowley skulking among the shelves, as if the angel had not expressedly marked them as his own territory years go.

There is, perhaps, no true need to fight it out, but Achillas is not far from the city, and Aziraphale is suspicious and not in the mood for any benefit of doubt. They nearly beat each other into the dust outside the city walls, but are interrupted before either one's body is damaged beyond repair.

Later, the night sky burns yellow in the light of the fires, reflecting among the wharfs and over the city and the great library. Aziraphale is staring helplessly at the glowing flames when he hears the scuff of familiar footsteps. He has the demon pinned against a charred wall in an instant, an elbow pressed against his throat.

"Easy there," Crowley hisses at him, roughly pushing him off, and it's a testament to how frazzled Aziraphale is that he succeeds so easily.

"Did you do this?" Aziraphale asks bitterly, and Crowley hisses again.

"Why would I do this?"

"To subvert my efforts in the fulfillment of my duty as Principality. To get back at me for stopping you earlier." Aziraphale's voice is dull, more tired than bitter at this point, and he does not have it in him to cling to disbelief when Crowley starts shaking his head.

"I liked that place too, you know."

"And now it's all gone," Aziraphale mutters distantly.

"...Not all of it."

Aziraphale should be defending himself, but can only blink as the demon steps close for a moment, shoving a bundle into his hands.

"This is..." Aziraphale stares at it, tracing the familiar lines with his fingers, then looks up. "Why would you have this?"

Crowley scowls. "I borrowed it."

"You mean to say you stole it. How- how many books have you-"

"If you want to put it like that. And anyway, if I hadn't, it would be nothing but ashes now, so it all turned out for the best, right?"

Aziraphale says nothing, cautiously pulling the book free of the rags, cradling it against his chest as he opens it. He recognises it as a scholar's rambling account of a journey along the Nile - he'd looked over it briefly back when it had been brought in. It is not terribly valuable, as books go. But even by itself, it is a treasure.

"...It's only one of thousands," he says quietly, and hears Crowley huff in exasperation.

"Better than nothing, isn't it? Do you want it or not?"

Aziraphale looks up sharply, suddenly on his guard again. "Why would you give this to me?"

Crowley shifts on the balls of his feet. "Well, I can't bloody well return it to the library, can I? And you like books."

"Not... not personally," Aziraphale admits, with a vague sense of guilt he cannot quite pinpoint.

"..How do you mean?" Crowley asks, brow furrowing. "You're always hanging around libraries. Don't tell me you don't... read."

"On occasion," Aziraphale protests, oddly defensive. "It is my duty to inspire enlightenment and see to it they grow in the reaches of art and science, not to... not to personally partake. They are only the words of mortals, at any rate," he finishes awkwardly, fidgeting with the book in his hands. It feels like a sacrilege, now, to be speaking like this with a survivor held in his very hands.

Crowley gives him a long, flat stare. "...Well... you should," he says at last, shuffling away.

Aziraphale looks down at the book again, holding it hesitantly. "..The cover is damaged."

"It's just dust," Crowley says quickly, and the deep burns guiltily become just that.

Aziraphale stares after him as he leaves, struck with the strangest sense that a puzzle piece is trying to force its way back into the final slot, only for the slot to keep digging its heels in.

Later that night, as he watches the flames die down, he reads the book from cover to cover, holding it gingerly, and then he reads it again.

The rambling scholar's account turns out to be at least in two thirds a personal diary, his life lost now to everyone but these pages.

Side by side with human scholars, Aziraphale later walks through the ruins, collecting the remains of books to preserve and restore what little he can.

When Crowley shows up two days later and offers to help, he accepts, and doesn't question it too much.

He supervises the transfer of the remaining books to the Serapeum, struggling to transform the temple into a worthy successor of what the Library used to be.

Whenever there is a lull, he reads, absorbing and drinking in what he had previously only skimmed.

By the end of the year, he has read every book he can find.

What will later be called the Plague of Justinian rolls through Constantinople, sweeping through the streets in stench and decay, Aziraphale catches Crowley slumped wide-eyed in front of a church. He suggests awkwardly that they go somewhere and have a drink; Crowley laughs at him and vomits.

It is both the first time and the last in a while that the idea is brought up.

The new millenium approaches, and with it Aziraphale can sense a change: He has his finger on the pulse of knowledge's flow, now, and can almost taste it in the dry paper when more and more quotations from the Book of Revelations begin to circulate; as conversations fill with the hushed din of whispered myths and recounted stories of omens and ill fate. It has been nearly a thousand years since the birth and death of the Son of God, and humans have ever been so fond of over-dramatising the round numbers.

Even so, Aziraphale is worried.

"We would have heard something about it," Crowley says reasonably mid-blow, as they are battling out their respective privilege to stay in the court of the king they have been both trying to influence.

"I'd hate to presume about you, but we've been kept somewhat on a need-to-know basis, Upstairs," Aziraphale observes, pausing to spit out blood. The fight is a formality more than anything – they are working in close quarters with the Enemy, and both need to have something to show for it.

Crowley grunts, sweeping forth with a blow that knocks Aziraphale off his feet. Unexpectedly, he does not follow through.

"We would have heard something, though," Crowley insists desperately, instead, standing over Aziraphale with his sword levelled at the angel's throat.

"...I certainly hope so," Aziraphale says gently, then rolls to knock the blade out of Crowley's hands.

The start of the new millenium comes and goes, with nothing overly Apocalyptic to show for it.

They go out to celebrate, in a way, drinking in the backroom as a coronation ceremony goes by.

When Crowley slips poison into his goblet and dumps his paralysed body into the closet, leaving him free to steal the crown and throw a political spanner into the gathering, there is something almost cheerful about it.

The next time they meet is in the Middle East, in the midst of the first few skirmishes that predate what will later be called the Crusades. And maybe it is the footsteps of War that they cannot help but trample over, and which trample over them in turn, but it takes them years of butting heads again to stop, as Crowley puts it, 'being utterly stupid about it'.

On a day not that different to any other, still sore from mutually inflicted wounds, they sit in a tavern and shake hands - and even now, none of it feels like a mistake. When they finally part ways, Aziraphale tries to decide if it is a deed of corruption or redemption, a miracle or foul magic.

In the end, he decides on both, but cannot say for sure which of them is responsible for which.

Crowley remembers the fourteenth century for its smell, Aziraphale for the sound diseased bodies make when he sets them alight. The demon spends much of it intoxicated, and the angel with a long-beaked mask obstructing his vision - and even with all that, it is still too much.

It does not bear further thinking about.

A century later, in Spain, they watch an elderly man's corpse pushed aside to make room for a frazzled-haired woman, her body bruised and broken as she is dragged to the stake, the kindling scratching her bare feet.

"She has done nothing evil," Aziraphale says stiffly, not quite hearing himself speak. "She will go to Heaven, at least."

Crowley turns away from him in disgust, and the angel does not quite notice he's gone until he spots a small snake uncoiling among the rapidly spreading fire. Its fangs sink into a bare leg and the woman's screams wane.

Aziraphale considers saying something among the likes of suffering strengthening the soul, but thinks better of it.

The years blur together, strangely enough – one war shifting into another as villages trickle outward into towns and cities. It seems almost interchangeable now, when they are seeing more of each other – easier to bear, perhaps, easier to forget as needed.

Crowley drags Aziraphale to Italy and makes him sit still in a workshop full of models and paint fumes, in silent observation as a painting is finished, the final touches bringing it to life.

The artist is brilliant, but aging, and it shows painfully when his hand trembles and a dab of white across the portrait's pupils emerges just a little too large.

Aziraphale can see the panic in Crowley's face before he spots the frustration in the artist's; he watches transfixed as the Serpent of Eden weaves forward, distracting the human with a clap on the shoulder and an overenthusiastic warble of praise for his skills, even as the briefest flick of a wrist erases the dab of white into what it should be. The demon gestures at the eyes then, to make his point. The artist looks startled, then relieved, a tad too easily for Aziraphale's liking.

"..You told him what you are," he accuses, when they finally leave, and Crowley pauses in the midst of a wistful look backwards to stare at Aziraphale, golden eyes wide.

"You did, my dear," the angel repeats, his voice more gentle now, and Crowley slumps slightly.

"So sue me, angel. He'd probably half-known already."

Aziraphale is dimly aware, somewhere, that as an agent of Heaven, the type of screw-up that involves being too willing to open up should probably be on his conscience. Something about the argument feels a bit backward, however.

"What else did you tell him?" he says distantly, and Crowley's face closes up.

"Not much," he answers, and they leave it at that.

Aziraphale spends most of the nineteenth century on probation in Heaven, following too little discretion involving Crowley and public restaurants and a mishap with a homophobic mob.

When he returns to Earth, it is with a very firm conviction not to send Gabriel a 'happy new millenium' card this time around.

Unexpectedly, he finds Crowley asleep, the clothes tossed around him outdated by at least several decades.

"Took your damn time," Crowley mutters later, rubbing his eyes, but Aziraphale is too busy marvelling over his perfectly preserved book collection in the next room to notice. He's fairly sure at least some of those copies had been damaged when he last saw them.

When a brilliant novelist cruelly murders his main character and then revives him, influenced in part by a large sum of money, Aziraphale breathes a sigh of relief and stops wearing the black band on his wrist.

The only clue leading him to deduce that Crowley had something to do with it is that the demon is more smug than usual - which isn't saying much, these days.

Most of the twentieth century passes in a blur of war. Aziraphale points out once, by way of conversation, that they are once again nearing the turn of the new millenium. Crowley mutters angrily and tells him to stuff it.

Aziraphale is quite happy to oblige.

Later on, there is a phone call, and a park meeting that should be like any other but isn't. Aziraphale finds himself setting fire to a traffic warden's notebook and remembering it, oddly enough, upon seeing a white dove flutter free of Crowley's hands eleven years later. Slowly, reluctantly, that last stubborn puzzle piece forces itself into place.

It is the end of the world – quite literally – streaked with rumbling concrete and yellow smoke, but when that final piece finally aligns himself, Aziraphale is too delirious with the epiphany of it all, of everything that has been staring him in the face all along.

"I'd just like to say..." he begins, and hopes sincerely, with all his heart, that Crowley will understand just how much he'd like to say, exactly, and how little time there is. "...if we don't get out of this..." oh yes, if... "That I'll have known, deep down inside, that there was a spark of goodness in you."

He has known, hasn't he? At times it had bobbed dangerously close to the surface, just shy of acknowledgement, only for him to stomp down on it with even more fury. But yes – deep down inside, he has always known. And it is now time to set things straight.

Crowley mutters bitterly, "That's right, make my day," and for once Aziraphale continues, undaunted.

"Nice knowing you," he says, holding out a hand, his fingers closing around Crowley's when the demon reaches to meet it. It is so much like that time in the tavern, a thousand years ago, and yet utterly different, because neither of them lets go.

"Here's to next time," Crowley says, and the angel – impending Apocalypse and all – is too busy beaming at him to point out that there likely isn't going to be one of those.

"And... Aziraphale?"

"Yes."

"Remember I'll have known that, deep down inside, you were just enough of a bastard to be worth liking."
Perhaps more than enough for that, and not quite deep enough, Aziraphale would argue, if they had more time. He doesn't look down at their hands, still clasped together in a gesture that grows less awkward and indispensable by the millisecond, or at the cracking concrete that spews infernal smoke and heralds the arrival of the Adversary.