Notes: This is my first fic in about 15 years but GO2 has destroyed my sanity.

This is also not a fic for the lighthearted. Explicit rape/noncon warning and dark themes throughout.

Crowley's confession came tumbling from his lips clumsily, stuttering over and around the word he still couldn't say. It burned in his mind as he dared to think the words.

I love you.

He couldn't say it. If he could, maybe the impossible choice he was faced with would become so much simpler. To give up the life he had fought and carved out for himself here on Earth, or to give up the one thing that made that life worth living? With all the words he had left to him, and every ounce of temptation he was able to muster he tried to urge the angel to stay. If not for the possibility of something between them, then the other things anchoring him to Earth.

The cherubic face in front of him crinkled sadly.

'Oh Crowley… nothing lasts forever.'

The words were like knives. He thought that everything they had built together was too valuable to throw away. Apparently, Aziraphale didn't feel the same. He had his answer, and Crowley felt his heart drop out of his chest and shatter on the floor. He had spent millennia erecting walls of self-defence around his emotions, cultivating a cold, uncaring exterior to hide how deeply he felt. The angel had always known how to find the weak spots in his armour. But in some cosmic joke the moment he had let down his walls and showed a sliver of his true heart, the angel had broken it instead. Her sense of humour was ineffable indeed.

Crowley hurriedly tried to regain his defence, his calculated exterior. Hiding eyes brimming with feeling once more behind his dark glasses, he made a flippant comment and lurched for the door.

Aziraphale was still pleading with him, but Crowley was resigned. It was obvious his feelings weren't returned. But three words in the speech, spoken in a voice cracking with emotion finally broke through to his brain

'I need you.'

A moment of vulnerability. Before the angel's face resolved once more into a composed mask. Heaven's good soldier again. But the momentary show of emotion was enough to embolden Crowley to make one final ditch effort to keep his angel. It was obvious their friendship would never be the same again. He had nothing left to lose.

'You idiot. We could have been us.'

Aziraphale couldn't even look at him. The demon's chest was filled with more emotion than he thought possible. Pain, rage, hopelessness, heartbreak, the thing that hurt to name. If he could just say that blessed word, would that be enough? He thought the pain might split him in two if he tried, the sanctity of the word would burn his forked tongue straight out of his mouth. Overwhelmed with it all and unable to express it, he lunged for Aziraphale. One temptation left to him, and if that didn't work at least he'd have stolen a single kiss. A final bittersweet memento of his millennia-long adoration, before an eternity of unknown torment.

He grabbed the lapels of Aziraphale's familiar coat, the one he'd been wearing for near on a century. He felt the delicate antique fabric crush beneath his grasp, as he pulled the angel to face him. He caught a flash of shock in the perfect sky-blue eyes before crushing his lips down over any further protests rising. He couldn't talk any more. Words were just making everything worse. Instead, he stole a kiss that was desperate, hungry, filled with all the words he couldn't give voice to. He was being much more rough than he intended, but he was so overwhelmed with feelings and couldn't think of any other way to express them. If only he could press them into the angel with his lips. If only he could make him understand.

He felt a fluttering of hands behind his back. Hands that were unsure whether to pull him in or push him away. Eventually, sensing that his final ditch temptation hadn't worked, Crowley pulled away.

The emotions flashing across the angelic face in front of him were indescribable. He hadn't seen so much turmoil on that perfect face in six thousand years. His hands were still flapping, unsure of what to do with themselves, they finally settled delicately on the plump, flushed lips.

Crowley couldn't move. Couldn't even breathe. He'd played the only card he'd had left to him. Now he just had to wait and see.

Emotions were still flashing across Aziraphale's face. Processing every moment of their long relationship in a new light. He started to shake. Just with gentle tremors at the tips of his fingers at first, but it spread and soon his whole body was racked with convulsions.

Crowley still couldn't breathe, but his eyes widened behind his glasses. He was locked in place, muscles coiled like a snake, unsure whether to flee or rush to the angel's aid. As Aziraphale dropped to the floor Crowley finally moved. Faster than a viper, he darted forward to catch the angel, still spasming uncontrollably.

'Aziraphale, angel, what's happening?' He blurted out in a panicked stream. In answer, the angel's eyes rolled back into his head so far that only the whites were visible. Crowley was screaming Aziraphale's name, reminded of a previous time he collapsed to his knees on this very bookshop floor. The fear rose in his chest. What had he done? Had he killed his best friend with a kiss?

Aziraphale's body stopped shaking, stiffening suddenly. His muscles tensed, pulling his soft body into painful looking contortions. A silent scream spread across his face as it pulled tauter than Crowley thought possible. He felt a sob shudder through his chest as his closest companion twisted into unrecognisable shapes. He reached out to stroke the taut cheek in front of him tenderly, hoping to impart some comfort. Stroking, he reached the feathery curls of hair framing the usually round and cheerful face and noticed something wrong. Very wrong.

The usually golden-white tufts were not their usual lustrous selves. Not just dishevelled, they were somehow different in colour. As Crowley turned a lock in his fingers he saw it. Like ink spreading across a pool of water, a darkness seemed to be spreading from the tips of the hair. Turning the golden-white curls a dark, dirty grey.

'No, angel, nonononoNO' Crowley's chest felt like it had been pierced with ice. He finally realised what was happening.

Aziraphale's wings shot out, knocking Crowley away and forcing him to drop the body that he'd been cradling with desperate tenderness.

'Angel, please, talk to me. Say something. Angel!' Crowley pleaded as he clambered back across the floor towards Aziraphale. He saw the shaking of shoulders and thought the seizure was starting again until he heard a low half-familiar chuckle. It was somehow Aziraphale's laugh yet not. All the twinkling music of it had been replaced with something discordant and bitter.

'I don't think you can call me that any more.' The words were laced with venom, making Crowley shudder. With a long, slender finger he found the jawline of the being in his lap and angled the head upwards. Crowley gasped as he looked in Aziraphale's eyes. Those once familiar eyes, the same grey-blue as the sky before a storm, that he had constantly gazed at secretly from behind impenetrable dark lenses. They were black, as if the pupils had blown completely to cover the entire surface of the eye. Looking closer, Crowley saw at their very heart something piercing and red, like a pinpoint of fire on a pitch-dark night. Aziraphale started laughing that hollow laugh again, with humour that didn't crinkle his eyes like his old laughter used to.

Crowley remembered every angel he'd ever seen immediately after their fall, recalled his own experience. The way that all the angelic love and joy had been replaced with bitterness and anger. He knew what was coming next wouldn't be pretty.

Crowley stood, dumping his now unfamiliar best friend unceremoniously onto the floor as he did. This only caused the low, rumbling chuckle to escalate into a howling cackle from the warped form on the floor.

'I'm sorry. I'm so, so sorry' muttered Crowley, to the memory of his angel.

'Whatever for, dear boy?' Crowley flinched, as the familiar term of endearment sounded like a mocking insult in his old friend's new voice. 'Now I can really have some fun'

Crowley started to back towards the door, totally lost. What were his options here? Smite his friend, and face the wrath of Hell? Walk away, and let this new and twisted form of Aziraphale spread evil in the world they had loved together? Rejoin the sodding angels to redress the balance? He snorted bitterly at that last one - just the thing Aziraphale had been begging him to do that could have prevented this whole mess. He decided to stay, to guide Aziraphale through the Fall. Being a demon wasn't so bad once you got over the shock and loss. Crowley had proved that.

'Why do you look so worried, dear boy? I thought you wanted this? Us?' The last word was spat poisonously, an accusation.

'Not like this Ange-' Crowley cut the word off as the mocking smirk widened on Aziraphale's face at the petname he could no longer use. 'Why?'

'Well, you wouldn't come to my side, so I've come to yours.'

'We were our own side, Aziraphale. You were… perfect the way you were' Crowley considered his friend again, his wings and hair now darkened fully to an inky black to match the terrible eyes. Things were still shifting and changing, his final fully demonic form not settled.

'Ah, but so stuffy. Always wringing hands about each little… pleasure' His lips curled up into a wicked, hungry smile. Crowley recognised it. It was a twisted form of delighted expression his angel used to wear when considering a particularly delicate and delectable dessert, only this time Aziraphale was looking directly at him.

Before he'd had chance to process his confusion, the newly fallen demon in front of him lurched forward. Crowley felt hands on his chest pushing him roughly backwards. He slammed into the heaped bookshelves behind him so hard that antique volumes crashed down around them, leaves coming loose as the spines cracked. Crowley's eyes filled with tears imagining the hurt the damage would have caused his angel, almost miracled the books back together before realising there was no point. That Aziraphale was gone now. Replaced by the demon in front of him. A demon that hadn't even glanced at the books, not tearing his hungry glare away from Crowley.

The hands pushing into his chest travelled upwards, one removing his glasses while the other closed around his throat threateningly. He was forced to stare directly into the dark, bottomless pits that had set up shop in his friend's face. In a reversal of their earlier encounter, this time Aziraphale pushed his lips hungrily down onto a confused and unsure Crowley. This wasn't how he wanted this to happen. He didn't know what to do, torn between revulsion at the perversion of the one he loved and just accepting it was the closest thing he was going to get. Instead, he stood frozen, unwilling to return the kiss but unable to break away either.

He heard something clatter to the floor as Aziraphale dropped his glasses, then almost jumped out of his skin when he felt fingers digging into his thigh. An unbidden moan, half protest and half pleasure, escaped his lips and the hand on his throat tightened. He felt as Azirphale's fingers grew, wicked and pointed talons where perfectly rounded manicured nails had once been. The claws raked his thigh, leaving ragged tears in his tight leather trousers.

Crowley tried to gasp for air as Aziraphale pulled his lips away, but was hindered by the hand gripping his throat tighter and tighter. His slitted eyes prickled as fresh tears sprang into the corners. He squirmed against the hands holding him with infernal strength, attempting to choke out a protest that got crushed in his throat. He batted weakly at the claw that continued to rake over his body, starting to draw blood where it tore skin as well as clothing.

'Isn't this what you wanted, snake?' Crowley could barely stammer in response. 'Am I not good enough for you any more? You were so high and mighty thinking you were better than the other demons. But we're the same now, and I can see it. There's no good in you at all.' The pressure crushing his windpipe would have already killed a human. But for him the heartbreak and guilt were so much worse than the physical pain he was in. Aziraphale had known him for so long, he knew exactly how to make it hurt.

Another crushing kiss came down on his mouth, teeth gnashing at his lips. Crowley stopped fighting. His arms fell limply by his side, despondently.

He felt a growl rumble in Aziraphale's throat, an unholy sound he never thought he'd hear escape his angel. Pulling back again, Aziraphale slapped him across the face so hard he saw pinpricks of light burst into his vision.

'Where's your hellfire gone, snake? It's no fun when you're so… limp' Crowley saw the demon suggestively eye his tight, ripped trousers. 'Maybe you need to be reminded where you started, and taste some forbidden fruit'. Crowley's eyes widened in fear and realisation. The wicked grin on Aziraphale's face grew impossibly wider, his teeth lengthening into sharp points.

Crowley felt the hand around his throat forcing him downwards until he couldn't stay upright anymore. He fell the last few inches painfully to his knees, hanging his head in defeat and shame.

'Not like that foul fiend' growled the voice above him as cruel clawed fingers curled through his dishevelled hair. With a sharp tug, his head was forced up and he was at eye level with Aziraphale's crotch. The soft, comforting fabric was so familiar, but straining in a way Crowley had never seen it do before. Crowley thought for just a moment he might be able to try and play pretend, without the sight of those wicked black eyes and spiteful smile to pull him out of the fantasy. He took a deep breath to settle his nerves, now that his crushed windpipe was free to do so. The acrid scent of brimstone hung in the air, stinging his nostrils and ruining any chance at fantasy.

Aziraphale used his free hand to rip open his fly at the seams, pulling out an engorged cock.

'Not like this…' Crowley wept again, feeling claws graze at his scalp, tightening their hold on his hair.

'Open wide snake, show me what that forked tongue can do.' spat Aziraphale. With a sharp pull on Crowley's hair, he released a gasp of pain and took the opening to plunge into.

Crowley gagged as his mouth was filled roughly. His throat, already sore from being choked, was now being punished from the inside. His eyes prickled again and he realised the tears were flowing freely down his cheeks now.

'Such a pretty sight' said Aziraphale with mocking tenderness, wiping away a tear with his finger. He sucked the finger, savouring the pain he'd inflicted. He moaned in the way he used to when sampling a particularly fine vintage, swirling the flavour around his mouth before looking back down at his weeping captive. Crowley averted his gaze from those terrible eyes, but then felt the claws grip his hair again as Aziraphale started thrusting into him, over and over. Each thrust smashed his head up against the bookshelf behind him painfully as he was ploughed into by the grunting, growling corruption of his only friend. Crowley tried to grab the hips of the beast and slow the thrusts, to give himself some relief, but it only made Aziraphale hungrier and more violent.

After what seemed like an eternity of torture, Crowley heard the cries above him grow high and keening. The brutal thrusts into his mouth became erratic. Aziraphale was reaching his climax. With a final, deep thrust the demon let out an unholy sound, like a wounded cry from a predator. Crowley felt thick, burning hot liquid fill his throat and mouth, before Aziraphale pulled out and painted his face with the final few spurts.

Crowley knelt, completely doused in shame and guilt. The only thing he'd wanted in over six thousand years was for that optimistic, truly good fool of an angel to be happy. Instead, in a moment of selfishness he'd ruined any chance of that.

Unforgivable, that's what he was.

Hope you… enjoyed? Maybe that's the wrong word. Always appreciate comments and critiques, especially as it's been so long since I've written anything. I'm the same username over on Ko-fi if you feel so inclined x

Much love, vix