Crowley was kissing Aziraphale.
Aziraphale was not kissing Crowley back.
Crowley pulled away from Aziraphale, breaking their kiss and stepping back as the angel stared at him in shock, his eyes wide. The air was thick with tension, years worth of unspoken thoughts and emotions clear on both of their faces.
"Why-" Aziraphale stammered, his hand rising to his lips to gently ghost across the spot where Crowley's lips had been pressed mere moments ago, "why would... why would you do that?"
"Why would I-?" Crowley blinked at Aziraphale, dumbstruck, "Because I love you, you-" Crowley threw his hands in the air, gritting his teeth as he stepped backward and away from Aziraphale, "you idiot!"
"I-" Aziraphale started, only to be cut off.
"No." Crowley exhaled heavily, years - decades, centuries, eons - of frustration coming swiftly to the surface, "No, you are going to let me talk." Crowley shoved a finger in Aziraphale's direction, jabbing it in the angel's direction to emphasize his words, "For once in your life, your very very long life, you are not going to interrupt me. You ssstupid Angel, you couldn't wait a single second to let me talk first. You had to go on about how your stupid Metatron wanted you to be the stupid Supreme Archangel and you wanted me to be a stupid angelagain, and I just can't-"
"Now, Crowley," Aziraphale huffed indignantly, "there's certainly no need for-"
"Angel." Crowley gritted out, holding his hand up in the universal - even for angels and demons - sign for 'stop', "I am going to say what I need to say. And you are going to stand there, silently, and listen. You are going to shut up and listen to me, because you owe me this. You owe me this, because you want to go and gallivant off to Heaven, and leave me behind. Because suddenly over sssix thousand years of us knowing each other doesn't mean a sssingle thing to you."
"I wasn't going to leave you behind, I wanted you to come with me, to be an-" Aziraphale protested, seemingly forgetting Crowley's whole tirade about not being interrupted.
"I don't want to be a bloody angel again, you-" Crowley turned around, gritting his fists hard enough that his knuckles turned snow-white as he fought a losing battle to keep calm, turning around to look at the angel that he had kissed only seconds prior with a cold gaze. "Thisss isss exactly what I am talking about!" Crowley's snake-like traits began to make themselves more evident as he began to grow more angry, as Aziraphale continued to make assumptions and not listen to him. "You can't, no, you refuse to just take a few steps back, open your eyes, and finally realize that they're all bad. Heaven, Hell, they all just want what's best for themselves. They don't care about humanity, they don't care about each other - just look how happily and quickly they tried to punish Gabriel and Beelzebub, they're leaders, and see that they certainly don't give a single God-damned fuck about you, Aziraphale. And they have proven it over and over again, explicitly to your face, and you still close your eyes and pretend that they're the 'good' side and hell is the 'bad' side."
"But..." Aziraphale's lip wobbled, his eyes darting around the room as he visibly fought the tears welling in them, "but if I agreed, if I was Supreme Archangel, I could change it, if I was-"
"No!" Crowley yelled, marching forward to press his shaking finger against Aziraphale's chest, the angel stepping back a half-step as he watched Crowley with wide eyes, "No, Aziraphale, you can't change them. It isn't a problem that's fixable. It's far too late for that, the system is corrupt, not just the people. Gabriel tried to change it, and they demoted him and wiped his memory. It's not just the angels, it's not just Heaven, it's God. God is apart of the problem, and nothing will change up there as long as that's true. Why can't you see it? Why do you refuse to see it?"
"I..." Aziraphale's hands fluttered around his chest, his eyes darting every which way as if he was searching for something to do, "I..." Aziraphale was shaking harder than a leaf in a storm, his shoulders rising to his ears as he pulled his limbs tight around himself, his lips wobbling and his nose reddening.
Without another word, Aziraphale burst into tears.
"Crowley," Aziraphale gasped, big fat tears rolling down his face as he sobbed, tears streaming from his face like water from a burst dam. His trembling hands rose to cover his eyes, muffling his shaking voice, "Crowley, what am I supposed to do? I'm an angel, what am I without Heaven?"
"And I am a demon," Crowley stood across from Aziraphale, not reaching out to comfort the distressed angel but not leaving the bookshop as he had been intending on doing earlier, "I've been quite alright without Hell. Remember Aziraphale, we might be an angel and a demon... but we aren't on Heaven or Hell's side, not anymore."
"We're..." Aziraphale hiccuped, his hands wiping away tears from his reddened eyes as he pulled them away, looking up to Crowley.
"We're on our own side." Crowley sighed, before carefully reaching up and sliding his glasses off his face, tucking them into his collar as he allowed Aziraphale to look him in the eye. "Angel, I love you. I have for a long time, but I didn't realize it. I will gladly and happily stand by your side, against anything that Heaven or Hell may throw at us, but you can't change me to something 'better' and more acceptable for your side, for Heaven. I will stand by you, on our own side, for as long as we're together."
"Together?" Aziraphale sniffed.
"Together."
Crowley reached out a hand, an offering that meant so much more than a simple union of their forms, an offering that was the culmination of all of time.
Aziraphale took it.
Back to my regularly scheduled sobbing and crying I go.