Ineffable husbands

The antichrist au

What if the mix up went wrong and Crowley took the extra baby with him, not knowing that the extra baby was the Antichrist. (Due to the mix up being well, mixed up)
Yes the baby is Adam from good omens. In this the baby Crowley takes with him to Aziraphale's is the Antichrist. No one knows how any of it happened)

A knock was heard on the door to the bookshop, it was very late at night and Aziraphale had finally settled in, reading from Hemingway while sipping on a steaming cup of cocoa.

"Oh for heavens sakes." He sighed setting the mug down and making his way downstairs.

Now the knocks had grown more and more impatient. When a voice from the other side muttered.
"Angel I swear if you don't get the door, I will miracle it off it's hinges."

Aziraphale's stomach did a little flip, from hearing the voice on the other side. But the fear of the safety of his newly painted door made him book it towards the door.
Only the fear of harm coming to the door. Not because a handsome demon was on the other side.

He opened the locks tremendously fast, slamming the door open.

"Crowley!" The angel smiled, his cheeks sporting a faint pink. Usually Aziraphale would answer the door fully dressed. Especially during the night. But it was nearly one in the morning. Instead he was wearing a button down nighty shirt and matching pants. (Which were both a light blue silk material) and slip on white slippers.

"Angel, there's a problem." Crowley stepped into the room, hair and clothes dripping wet.
Aziraphale examined him.

"You're getting water all over the carpet, that's definitely a problem."

Crowley sighed, snapping his fingers.
He was now completely dry, even the spot on the carpet under him.
"There. Now angel onto business. The Antichrist is happening."
Crowley set the mysteriously wrapped up basket on the table.

Aziraphale gasped moving towards Crowley.
"Are you sure?"
Crowley rolled his eyes. Even behind his dark sunglasses Aziraphale could see them roll.
"Yes angel, I helped deliver the baby." Aziraphale's eyebrows knit together, the mere thought of Crowley delivering a baby was perplexing.
"You did what?" Aziraphale was blinking rapidly, then Crowley finally caught on.

"I didn't deliver deliver the baby, Hastur handing the baby and the basket over to me and I just had to give it to the sisters!" Crowley face turned pink and embarrassed as he tumbled quickly over his words.

"Did Hastur deliver the baby?" Aziraphale asked amongst at the scattered mumbling Crowley was saying.
He paused, his glasses falling down his nose a little.
"...I actually don't know..." Crowley looked at Aziraphale, the two gave a knowing look to each other and immediately burst out laughing.
There was a calm atmosphere once again around the shop as the two laughed. Unbeknownst to Aziraphale, was the baby in the basket.
After a bit of talking about the Antichrist, Aziraphale walked over to the basket.

"So what's this then? I'm hoping it's some fresh baked bread." Aziraphale hastily moved the linen blanket out of the way to examine the parcel.

"Wait, Angel!" Crowley yelled out, basically running to the basket. But it was too late.
Aziraphale was looking down at the peacefully sleeping baby.
His mouth opened as if to say something, but nothing came out. He looked back and forth between Crowley and the baby until-

"Crowley did you Steal this baby?!" Aziraphale yelled, complete and utter horror on his face.

Crowley started to explain.
"Well you see it wasn't necessarily stealing if they were going to dispose of the baby. More like saving the baby if you think about it. Aziraphale. Angel. Stop screaming! You will wake the devilish monster! Angel please!" But Aziraphale couldn't hear over his flustered panicking. Saying things like "oh my heavens!"
"And don't panic" and "Crowley you idiot!"