“Here, try some of this, angel” Crowley passed the tiny little sake cup over to Aziraphale, and their fingers brushed as the angel took it.
Aziraphale didn’t even flinch, though as always, burning, hellish pain seared through him at the contact. He only smiled and raised the cup to his lips. “Oh, I say, that is nice. Something a bit herbal in it. Juniper?”
“Cedar, I think, says it was finished in cedar barrels.”
“How delightful. Here, you can have it back now.” He held the cup out to Crowley, who shook his head.
“Nah, ‘s fine, angel. I’ve got more.” He gestured at the flight of little sake cups lined up neatly before him. Aziraphale had just the one, though he also had a massive platter of assorted nigiri, while Crowley was picking at a single serving of scallops.
Aziraphale nodded and took another sip, wondering in the back of his mind if Crowley really had decided he didn’t want the rest of the sake, or if he merely didn’t want to risk touching Aziraphale again so soon.
The angel could remember every single time he and Crowley had touched, since horrible pain was an excellent memory aid. The earliest times had been startling, making both parties flinch and swear to never forget themselves and touch again. But over the centuries they inevitably had, and at some point the pain had stopped mattering all that much, somehow.
Minds being the illogical and impractical things they were, though, Aziraphale frequently pictured doing quite a lot more than simply touching. His frustration at how unreachable those fantasies were had only served to further cement those tiny scraps of physical contact that he had gotten in his memory. He wasn’t sure when the fantasies had started, really, they’d crept in bit by bit, but certainly for the last few hundred years, whenever he touched Crowley he was tormented by images of things he could never have. And during his rather rare dalliances with some interesting mortal, he found his mind inevitably drifting to thoughts about a certain demon rather than the human he was actually with.
But “demon” was the problem, of course. Celestial and infernal natures simply didn’t mix. Just the faintest brush of skin on skin was agony. Aziraphale suspected that trying to kiss would probably discorporate one or both of them. Probably Crowley, and possibly permanently, which was one large reason why he hadn’t succumbed to his fantasies and tried it anyway. He suspected that his saliva probably constituted holy water, and he couldn’t risk it. He could ignore the pain of brief contact, but he couldn’t risk actually hurting Crowley.
They’d never done more than brush fingers together, save for in the events surrounding the Armageddon-that-wasn’t. There had been an improbable bus ride, when they’d held hands for a few blissful, blistering seconds, unable to keep from wanting the contact, however terrible it might be. And they had held hands again to swap corporations, which had been fiddly business, trying to switch their bodies around without letting celestial or infernal energies come into contact. 
Touching was simply not something angels and demons were meant to do.
Aziraphale knew the demon felt something for him, of course. He could sense when a being was loved just as well as when a place was loved, and so he knew that Crowley had been slowly falling in love with him down through the centuries. Early on he’d pushed it aside as something wrong and aberrant, something an good and righteous angel could never possibly return, but eventually he’d realized that he did return it, and since the end of the world some ten months past he had started to think that it might even be safe to return it. What use was that, though, when they could barely brush their hands together? They were best friends, weren’t they? That was as close as they could be. Even if he someday declared his love for Crowley and let the demon declare his aloud in turn, they couldn’t behave as lovers. It was easier to let any notions of “love” lie unspoken.
Crowley’s voice made Aziraphale realize that he’d been sitting there, sake cup in hand, not touching his sushi for some time. “Oh, sorry, my dear. Just woolgathering. Did you say something?”
“Nothing important. Want a scallop?” Crowley held out the little bundle of seaweed and seafood in his chopsticks, and Aziraphale opened his mouth and let the demon put it in, the chopsticks keeping them both safe. Aziraphale pushed the thought of how lovely it would be to have Crowley feed him by hand for perhaps the ten thousandth time and turned his mind to the flavors dancing across his tongue as he chewed.
“Simply delicious. Thank you, my dear.”
“‘S no trouble, angel,” Crowley replied, smiling, and they went on just as they had for literal ages, sitting side by side, not quite touching.
Aziraphale said goodnight through the open car door, and then Crowley was zooming off into the London night. At least at this hour he was marginally less likely to hit somebody. Aziraphale turned and went into the bookshop. Inside he considered a cup of tea, or cocoa, but his stomach was still stuffed with sushi and sake, and he decided he didn’t feel like miracling the pleasantly full sensation away, but that adding anything further would probably push it past pleasant into unpleasant.
So he pulled out a book from a stack beside the register that was his personal “to read” stack and settled into a comfortable chair to begin passing the night.
He’d barely turned a page when he noticed an itch, immaterial but intense, hovering just behind his shoulderblades, and sighed deeply. He’d been a little itchy yesterday too, and had hoped some momentary ethereal wind had just ruffled his feathers, but the persistence and increasing intensity of it meant that he was beginning to molt. The longer he ignored the itching, the worse it would get. Right now it had already blossomed into something that was actually painful, a little burning speck at the core of a larger itch on each wing that was utterly maddening.
Giving in to the inevitable, Aziraphale scooted forward in the chair and manifested his wings. They both itched terribly along the upper “arm”, where the small coverts lay. He pulled one wing forward and scratched luxuriously, then sighed as he saw several little feathers drop free. Definitely molting.
Despite all the scratching, though, the speck of pain wasn’t easing.
Aziraphale frowned, combing his fingers through his feathers over the spot. He felt the hard point of a pinfeather pushing through the delicate skin beneath its protective layer, and the pain was centered there. It didn’t even feel like an itch anymore, it felt like something burning, like the pinfeather was an actual pin, red hot and being poked into his skin. Had it somehow gotten infected? He wasn’t sure that was possible, but something was definitely wrong. He parted his feathers with his fingers to look at the spot, and sucked in an immediate shocked gasp.
He knew what pinfeathers looked like coming in, they were basically feather shafts, hard little points flushed with blood for growth that would develop feather barbs as they grew. This was definitely a pinfeather, a narrow barb pushing up through the skin, but where every other pinfeather Aziraphale had ever grown had been translucently pink, his white coloration showing the blood within, this one was opaque and jet black.
He checked the other wing, since pinfeathers always grew in pairs, and found the other painful itch had a second pointed black nub at the heart of it as well.
Demon’s feathers that burned against his skin with all the hellish fire of Crowley’s touch.
Angels, like all winged things, need to occasionally molt, shedding their old feathers to grow new ones. This is an annoying process which tends to make them snappish. But when Aziraphale goes into his first molt after the Apocalypse that wasn't, it's a bit different than any other molt he's ever had, and he gets more than merely snappish.
Or in other words, Aziraphale Falls, one feather, one sin, at a time.
A little Good Omens story! This is complete, at ten chapters long. I'll try to upload one every day until they're all up.
I figure this is a good story to share this month, as it's about re-learning your identity, and also features a literal Pride parade. (And the "deadly sin" of pride, too!)
The last chapter does contain a sex scene, but it's much more "literary" and less erotica than usual for me, so it won't actually move beyond mature, and the rest of the story is very much All Audiences.