It was Saturday the first of September 1666, and an angel was walking down Pudding Lane. Aziraphale had found a rather nice bakery on the lane and had quickly got to know the owner, Thomas Farrier. He was now often treated to free cakes in front of the roaring bakery fire. The angel hummed as he walked, feeling content.
A flash of something dark down a side street, and Aziraphale's humming stopped abruptly. He peered down the dark alley.
"Show yourself!" Aziraphale's voice quavered, but he stood his ground.
"Hello angel," a voice crept back through the darkness like a snake in the grass, "long time no see."
"Crowley! You gave me a fright!" said Aziraphale indignantly.
Crowley sauntered out of the darkness and fell into step with Aziraphale, who was trying to walk away.
"So," he purred, "how are you? I don't think we've spoken since, hmm," the demon considered.
"The globe theatre," Aziraphale finished for him.
"Oh yes," Crowley smiled, "that was nice."
"What are you doing here anyway?" asked Aziraphale icily. Part of the arrangement was that Crowley wasn't supposed to just visit him on a whim. He didn't want there respective head offices to find out they'd been fraternising.
"I came to see you," Crowley replied, as if the answer was obvious, "we are friends after all."
"We are not friends," Aziraphale retorted, his eyes darting from side to side as if walls had ears, "You're only supposed to speak to me about business. The Arrangement."
"I was bored," Crowley flung an arm around Aziraphale's, shoulders, "I missed you angel."
"You aren't capable of that kind of thing," Aziraphale said, more to convince himself, as he pushed Crowley's arm off him. The demon was teasing him, playing with him. And yet, there was something real in his snakelike eyes. Maybe Crowley was being honest. Aziraphale had been getting lonely too if he was honest. Sometimes he had even considered finding the demon, just for someone to talk to. Was Crowley doing just that?
"Well I'm going to this bakery," Aziraphale explained, "but," he added, almost hopefully, "I could come and find you tomorrow?"
Crowley smirked by way of agreement, and disappeared back into the dark.
Aziraphale walked on. He was oddly excited to see Crowley tomorrow.
…
By the next day, London was in flames. The fire started soon after midnight, in the early hours of the second of September. The flames licked at the sides of the wooden houses, which were dry from the recent days of hot weather. They raged through the streets, obliterating everything in their path. A large part of London was unrecognisable by two in the morning. A warren of charred husks.
The first building to burn was Thomas Farrier's bakery, on Pudding Lane.
…
Once again, an angel walked the streets of London. Aziraphale was impervious to the flames all around, but there was little for him to do for the helpless humans all around him. He ran through the burning streets, trying to help without getting discorporated, draining his powers as he tried to keep himself from choking on the thick smoke.
A fire like this could only have been caused by a demon, and Aziraphale knew one demon who had been on Pudding Lane just a matter of hours before the fire started. He couldn't believe that Crowley could be so cruel. Clearly, he had underestimated the demon. He had thought that Crowley was good, or as good as a demon can be. But he had been wrong. Wrong to trust someone from the other side. Wrong to make an arrangement with him. Wrong to ever believe they could have been friends.
But he had to put a stop to the fire. Which meant he would have to find Crowley. He couldn't do this alone. Maybe he could convince the demon to take back his curse. Maybe. He had to try.