Kemonomimi
The doorbell to Aziraphale's bookshop rang out through the quiet building. "Just a moment," he called. "You should know that we close in fifteen minutes though."
"It's me angel!" yelled back Crowley. "Can I come in?" Aziraphale quickly agreed and heard the door open and close as Crowley shuffled into the room.
He turned around to see a thoroughly embarrassed Crowley. He was wearing an out of fashion top hat that was still a little dusty. It likely hadn't been worn in decades, so that was reasonable.
"Bringing back the 1800's, are we?" teased Aziraphale.
"Buzz off Aziraphale. I'm only wearing them to hide the… um…" he trailed off a little. Aziraphale raised an eyebrow. "Promise you won't laugh?" he said.
Aziraphale quickly agreed and Crowley removed the hat, revealing a pair of neat brown cat ears. "Downstairs messed up my physical form after I discorporated the other day. They accidently combined my body with another Demon's animal form… It was a cat."
"Evidently." Aziraphale couldn't resist the urge to smirk.
"You said you wouldn't make fun of me!"
"I'm not," insisted Aziraphale. "I just think it makes you look cute." He stood up on his tip toes and made a move to touch the ears. Crowley would have resisted, but he was too exhausted to do much.
"They're soft," remarked Aziraphale, settling back down on the ground. Crowley rolled his eyes but said nothing. "When will it get fixed?" he asked.
"Don't know. Beelzebub said it might take a day or two to straighten everything out. Fill in all the paperwork. All that. I can't really be outside because, you know, cat ears. Can I stay with you for a day or two?"
"Most certainly," said Aziraphale. "Do you want something to drink?"
"I have a coffee."
Aziraphale set the drink down on the table in front of Crowley a minute later. Crowley's cat ears twitched forward with interest at the familiar smell. Aziraphale couldn't stop himself from giggling a little.
Immediately, Crowley's ears began flicking back and forth. Aziraphale found his thoughts coming back to a book he had read about animal behaviour. If he remembered correctly, twitching ears were a sign of irritation.
"I'm not laughing at you dear. Your ears are sweet, is all. Sweet like you."
"I'm not sweet."
In that moment, Aziraphale realises just how catlike Crowley was. He was abrasive with strangers, cuddly with those he liked, and overall, slightly antisocial. He took long naps (Aziraphale still remembered the time when he didn't see Crowley for a century, which Crowley had excused as a prolonged cat nap) and enjoyed the night.
Crowley was more of a cat than he had first thought.