As the summer days shortened, so did the amount of time Crowley spent in his own flat. Without either one of them actually saying anything, the angel and the demon had come to an understanding about their new living situation.
The flat over the bookshop had become much larger inside than it was on the outside, and there was now a lush balcony decked in shivering greenery. There was more hard liquor in the building than Aziraphale had ever acquired for himself, not that he minded.
But Crowley went back to his previous home every once in a while, maybe for a day each week or so. Not enough to worry the angel, but Aziraphale eventually grew curious and decided to ask about it one autumn afternoon when the sun was hazy in the sky and the clouds were tinged with orange.
"I suppose it isn't any of my business, Crowley, but why do you still go back to your flat? There's plenty of room here now, and you're always most welcome."
The demon shrugged, swishing a glass of whiskey.
"Uh, you know. Old habits die hard and all that."
"Habits of doing what? All the plants are here."
Aziraphale thought he was about to discover some wily, secret thing that Crowley did away from him, all alone, something most diabolical and fitting of a demon. And he was quite excited to find out what it was. If Crowley was actually going to tell him, of course. But he didn't understand the demon's next sentence at all.
"Oh, you know. You wouldn't like it. Get back to my roots, as it were. Sometimes I just like to hsssss" And here he hissed exactly like the serpent he had once been, sticking out his long tongue rather both comically and erotically.
This confused Aziraphale on levels both cognitive and emotional. He tore his eyes off Crowley's tongue.
"You like to hiss?"
"Ehh, among other things. Slither about, bask in the sun."
Aziraphale looked even more puzzled for a second before he realized what Crowley was talking about. It wasn't quite the dastardly scheme he'd imagined, but there was something ridiculously charming about the idea of seeing his demon as a snake.
"Oh! That, right. Of course! Of course this body must be uncomfortable to you sometimes. I wouldn't mind at all, my dear."
"Sometimes I shed. And eat rats. I really don't think you'd be too fond." Crowley had never, ever let anyone else see him as serpentine since the garden. Humans had immediately decided they hated snakes, perhaps for good reason, and there was too much vulnerability to the whole business. He knew Aziraphale wouldn't have quite the same reaction, but he feared a look of disgust or horror on the angel's face.
"Really, I wouldn't mind. All creatures, great and small. And I've always wanted a pet!"
Aziraphale thought the look of shock on Crowley's face was priceless.
"What? For fuck's sake, angel, I'm the serpent of the garden, not a fuzzy bunny. And I am most definitely not a pet." He spat out the last word.
Aziraphale blushed. "Yes, no, I know. I didn't mean to say you'd be a pet, not at all, just. It would be most intriguing to see you in that form. I think it'd be quite fun."
The demon grimaced. This hadn't gone his way at all. Leave it to Aziraphale, creature of unadulterated love, to turn his most disgusting habit into an exercise in bonding and affection. Absolutely revolting.
The next morning, Aziraphale left Crowley in bed to open the shop. He closed the door softly on the way out, looking over his shoulder at the demon and smiling contentedly.
A couple of hours later, Aziraphale was engrossed in a book behind the counter. He felt something bump, softly, against his ankle. The angel looked down.
"Oh! Crowley! You've woken up." He paused awkwardly. "Would you like to be up here, then?"
The snake lifted its neck, forked tongue flicking the air.
Aziraphale picked him up gingerly, setting him on the counter. Crowley slithered over to the book the angel had been reading, sprawling himself across the pages.
"Oh, I've just the thing!" Aziraphale snapped his fingers gleefully, and the old desk lamp turned into a much more powerful heat lamp. The snake yawned and the angel thankfully remembered that he shouldn't exclaim at how adorable that was.
A.Z. Fell and Co. began to experience a new wave of popularity. More and more people started dropping by to query Aziraphale on his extensive knowledge of herpetology, and others came by just to ogle at Crowley's hypnotizing scales. This was all fine and well to the demon; he didn't mind being admired and Aziraphale loved to share knowledge. There was one rule, however, which Crowley set on day two.
He had taken to slithering about the bookshelves, surprising anyone who dared to pick up one of Aziraphale's personal collection. He found it a fitting expression of mischief, and it brought such a lovely smile to the angel's face.
A particularly curious human had spied him lounging on copy of The Picture of Dorian Gray. It was a first edition, pristine, and Crowley was curled up on it as if he owned it.
The offending human had tried to pick him up and pandemonium ensued. Crowley writhed and wriggled, unleashing a hiss that no snake of that size should have been able to make. The man dropped him in shock, and by this time, Aziraphale had run over, divine fury on his face. He extended a hand down to Crowley, who leapt up and wound himself around the angel's arm tightly.
"I'm afraid I'm going to have to ask you to leave." Aziraphale's voice was cold and intimidating, and even Crowley shuddered a little as he nudged the angel's elbow softly.
The man escaped the shop with a holy fear and Aziraphale changed the sign in the window to closed.
The next day, there was a new sign in the window, one which warned in capital letters that the snake was not, under any circumstance, to be poked, prodded, or touched.