Crowley has had much, much worse assignments than working at the Dowling residence. Everything is remarkably normal, which helps with his and Aziraphale's goals immensely. Thaddeus, unlike so many politicians, doesn't seem to be shtupping anyone but Harriet, and Warlock seems a perfectly average boy, at least so far.
Aziraphale immediately makes friends with the rest of the staff, because of course he does. Crowley would rather put the fear of the Devil in them; being friendly wouldn't work with the whole image he's cultivating, untouchable and ruthlessly competent. He has to be aloof for it to work, but aloof is a thing he's very good at.
It is no surprise to anyone that Aziraphale cozies up to the chef immediately. He's a young upstart named Devan; the Dowlings poached him from some restaurant in America, presumably paying him a ridiculous amount to stick around. Devan is, not to put too fine a point on it, a bear of the highest degree. He has a lush beard, radiant hair, and hairy arms of the sort that look good on a certain type of man, and he's heavy-set in a fashionable way. He has a lovely smile and looks like he could bench-press Aziraphale, who looks transported when he bites into one of Devan's tarts.
In short, he is nothing like Crowley.
Crowley is not unaware that Aziraphale sometimes has sex; he didn't go to all those discreet clubs for discreet gentlemen just to dance the gavotte. Crowley doesn't judge him for that, naturally- how could he? He doesn't care if Aziraphale has sex with a dozen men at a time; he just doesn't like that he knows about it.
He particularly doesn't like that it's going on right in front of him. He doesn't know if he can just sit here and watch it happen. It makes him think too hard about what Aziraphale's body felt like underneath him when he was the one, and Crowley can't even get drunk and forget, not when he's too busy trying to shepherd Warlock to the exact correct degree of evil.
This continues for quite some time. Crowley's consolation is that their work is going quite smoothly; when he checks in with Aziraphale, Aziraphale is of the same opinion. Crowley doesn't know how he even has time to have an opinion on it when he's too busy hanging around the kitchens, but Crowley's not going to say that.
This is Crowley's stated position until he actually goes to the kitchens one evening. The place smells like good food, not that Crowley's particularly interested in such things; he's here to procure a treat for Warlock to reward him for a particularly mean thing he said.
Devan is standing in front of the oven, which is to be expected; Aziraphale is sitting on a stool nearby, and Crowley rolls his eyes.
"I'll be back in thirty," Devan says, taking off his apron.
"A bold choice," Aziraphale says.
"I'll sit here and open the oven six times if I stay," Devan says.
"Why don't I keep an eye out for you?" Aziraphale says.
Devan smiles. "I knew I could count on you."
Aziraphale smiles back, and something in Crowley, some mental tether, perhaps some kind of underwire, snaps.
"Oh, hello, Nanny," Devan says, noticing him. "Can I help you with something?" Crowley just makes a dismissive gesture, stalking over to Aziraphale. "Uh, okay, guess I'll see you later, then."
"With me," Crowley says, walking into the pantry, and Aziraphale follows him.
There is a door, and Crowley doesn't shut it. Instead, he grabs Aziraphale by his ridiculous smock; Aziraphale seems confused, and Crowley doesn't let go.
"What are you doing, angel?" Crowley says, pulling Aziraphale towards him.
"I don't know what you're talking about," Aziraphale says.
"You know exactly," Crowley says. "How many times have you been in here today?"
"Devan's making tarte tatin aux poires," Aziraphale says. "Of course I've been in here more than once."
"I don't want to hear another fucking word about Devan," Crowley says, and he's so frustrated that he kisses Aziraphale as hard as he can. Aziraphale makes a startled noise, like he has any right to be startled, but he puts his arms around Crowley's waist. Crowley doesn't get any less frustrated, so he pushes Aziraphale up against the shelves. His skirt is too tailored to spread his legs very far, so he spreads Aziraphale's instead, shoving them open to stand between them.
"Uh," a voice says from behind them.
Crowley pulls away, ready to take out his annoyance on whoever it is, and it's with a great deal of satisfaction that he realizes it's Devan. Crowley is a hair's breadth from saying something bitchy and triumphant, when he realizes that Harriet is standing behind Devan, looking displeased.
"Hi," Crowley says with a smile that's hopefully reassuring.
"I'll see both of you in the study," Harriet says, then she turns on her heel and walks away.
"Shit," Aziraphale says.
"I'm gonna go," Devan says, and he quickly leaves as well.
"How is my hair?" Crowley says, patting it down.
"That's what you're worried about?" Aziraphale says. "I just got caught with you making out with me by the Earthly mother of the Adversary, who might throw us out of her home right now, ruining years of planning, and you're worried about your hair?!"
Crowley opens his hands. "It's all about the look," he says, the wheels already turning in his head. "Now straighten your clothes and follow my lead, no matter what I say."
Crowley adjusts his posture, taking up the prim and upright stance of the perfect nanny, and marches to the study, Aziraphale trailing in his wake. The door is already open, but Crowley raps on the jamb before entering.
"I'm going to give you a chance to explain before I contact Thaddeus," Harriet says. "You'd rather explain it to me, because Thaddeus is going to have a lot to say about the American values that we're trying to raise Warlock with."
"I think it's time that we come clean," Crowley says, taking Aziraphale's hand.
It's not actually possible for an angel to have a heart attack. The actions of their bodies just don't work that way; they're animated differently. But no angel in all of history comes as close to it as Aziraphale does in that moment.
"You see, Francis and I," Crowley starts, giving Aziraphale a look that is both loving and perfectly conveys that Aziraphale should keep his trap shut. "Well, the truth is that we've been married for some time."
"Married?" Harriet says, puzzled. "Why didn't you say anything until now?"
"There's such a prejudice against married women serving as nannies," Crowley says. "Since we were fortunate enough to find employment in the same place, we thought it best if we weren't quite honest."
"Oh yes," Aziraphale says. "Me and Crow-" Crowley gives him a look of panic. "That's my nickname for her, you see, ma'am," he covers. He puts a knuckle to Crowley's chin, pushing it to the side in an affectionate gesture. "My little Crow and me, we needed the work, so we kept it to ourselves."
Harriet's face breaks out into a grin. "Why didn't you just say?" she asks. "It's not the nineteenth century anymore. We're so happy to have the both of you."
"I can't tell you how thrilled I am to hear you say that," Crowley says, putting his free hand to his chest.
"I'll arrange to have your rooms combined immediately," Harriet says. "Would you prefer to be in the house, or should I have Nanny's things moved to the gardener's space?"
"House," Aziraphale says, at the same time that Crowley says, "Garden."
Crowley laughs lightly. "Let me confer with my husband for a moment."
"Of course," Aziraphale says, leaning over to Crowley.
"You do not want this house to hear what I am going to do to you when I get you alone," Crowley hisses into his ear.
"The garden will be just fine," Aziraphale says to Harriet.
"Now, I will have to ask that you keep anything like that to your rooms from now on," Harriet says.
"Oh, of course," Crowley says. "Please forgive us for the lapse in judgment. We are so dreadfully sorry, and nothing of the sort will happen again."
"Apology accepted," Harriet says, with an indulgent smile, and Aziraphale puts a hand on Crowley's back and gestures him out, following behind him.
Down the hall, three of the staff are lurking in a dark corner, just within earshot of the study.
"Why am I not surprised that the two weirdest people here hooked up?" Marie, the sous chef, says.
"Is anyone going to tell her her husband is gay?" Nan, the housekeeper, says.
"You never know," Devan says affably. "Maybe he's bi."
Aziraphale and Crowley miss this exchange entirely. They are both focused on getting out of the house, through the garden, and to the outbuilding where Aziraphale is living. It's a light and airy space; it strikes Crowley that it's perfect for who Aziraphale is pretending to be and far too ascetic for who Aziraphale actually is.
That's about as far as Crowley gets, because he's still very pissed and weirdly horny. "Can we talk about this?" Aziraphale says, with a plaintive note that almost, almost breaks Crowley's resolve.
"What's there to talk about?" Crowley says, stripping out of his jacket and shirt and tossing them carelessly away.
"There's a lot to talk about," Aziraphale says, though he starts undressing too. "Starting with why you're so angry with me."
"I'm not angry with you," Crowley lies, and he shoves Aziraphale onto the bed. Aziraphale backs up, making room for him. Crowley's skirt hits the floor, his panties following, though he leaves his stockings on.
"Are you, um," Aziraphale says, looking illustratively at the area between Crowley's legs. "That is, if you-"
"Hold on," Crowley says, because Aziraphale's going to keep stammering and acting bewildered until Crowley has a dick again; he's too polite to force the issue. The feeling of changing his anatomy is positively bizarre, but Crowley ends up as Aziraphale is accustomed to, at least in the crotch.
"Do something about this," Crowley says, making a motion that encompasses his face. Aziraphale's features resolve into the look that Crowley vastly prefers. He reaches back to unhook his bra. "Breasts or no breasts?"
"Ah, breasts are fine, I think," Aziraphale says, undoing his trousers and pushing them down and off, his briefs with them. "Not to be too presumptuous, but there's lubricant in the nightstand-"
"Of course there is," Crowley says; his anger softened a little while he got undressed, but now it's jacked back up to full. "Of course there fucking is." He pulls the handle on the nightstand drawer, so hard that it almost falls out; there is indeed a bottle of lube, just sitting there, mocking him. He snatches it up anyway, shoving Aziraphale's legs apart to kneel between them.
"I do wish you'd tell me what this is about," Aziraphale says, watching as Crowley pours the lube onto his fingers. He lets out a gasp as Crowley pushes a finger inside of him, no preamble.
"You know what this is about," Crowley says. "You have to know what this is about, or you wouldn't be doing it."
"Please don't be that way," Aziraphale says, though he spreads his legs wider as Crowley adds another finger. "Please tell me what's wrong."
"I'll tell you what's wrong," Crowley says, and Aziraphale bites his lip as Crowley fucks him roughly with his fingers. "What's wrong is you swanning around here, lording it over me with other men."
"I have no idea what you're talking about," Aziraphale says.
"Yes, you do," Crowley insists. He hikes Aziraphale's legs up, pushing into him in one thrust; Aziraphale's head falls back, his mouth open, panting. "How much have you been doing this, huh? Do you bring Devan back here?"
"Devan?" Aziraphale says, more confused than anything, but it makes Crowley see red.
"Not Devan," Crowley says. "Never again, Devan." He bends down, close enough that his breasts press against Aziraphale's chest. "From now on, only me."
"Crowley," Aziraphale sighs, and Crowley fists a hand in his hair, pulling it back so he can bite down on Aziraphale's neck.
Crowley absolutely fucks Aziraphale as hard as he possibly can. It would be too much for anyone who isn't a fellow basically-immortal being, but Crowley knows he doesn't have to hold back. All those humans that fucked him before are nothing; Crowley wants to wipe them away with every stroke, rewrite it all, prove to Aziraphale that there's never been anyone like him, only inferior knock-offs and wastes of his time.
Aziraphale makes no move to stop him, no move to do anything but get more. He wraps his legs around Crowley's waist, pushing back up against him. He's eloquent normally, but he seems to have nothing to say, nothing but moans and repetitions of Crowley's name. He says it like he's begging, and Crowley only gives him more. His stockings are a lost cause, and his hair is falling out of its carefully sculpted waves, hanging down into his face. He doesn't care; the only thing he could possibly care about is Aziraphale.
Aziraphale comes with a cry, shooting onto his stomach, and Crowley doesn't stop. He's trying to prove a point, and he's too wrapped up in it to think about anything else.
"Crowley," Aziraphale says gently, stroking his cheek. "Let go for me."
Crowley bites down on his lip so hard that he draws blood. It seems to rush back in, the sensation, and all he does when he comes is gasp, the tension rushing out of him in one big wave.
It takes a while for both of them to catch their breath; after some twisting and turning, they end up with Crowley on his back, Aziraphale resting his head on Crowley's breasts.
"Well," Aziraphale says. "Let no one say we didn't consummate our marriage."
"I shouldn't have done that," Crowley says; remorse is not his style, but he's feeling it right now. "Fuck, I'm sorry."
"Did you really think I was sleeping with the chef?" Aziraphale asks.
"Yes," Crowley mutters.
Aziraphale chuckles. "No one but you could possibly be attracted to me when I'm done up like Brother Francis."
"You've had weirder facial hair," Crowley says.
"Next time, an adult conversation, then the wild sex," Aziraphale says.
"I can go so much wilder," Crowley says.
"There isn't a doubt in my mind, dear," Aziraphale says. "You know, if you'd only have asked, I'd have said yes."
"To which part?" Crowley asks.
Aziraphale laces their fingers together. "Any of it."
"I hope I didn't scare you," Crowley says.
"You haven't scared me for a long time," Aziraphale says. He sighs. "We do need to get our stories straight, however. When people inevitably ask, you can't say we've known each other since the Garden."
"But what if we did," Crowley says. "They'd never believe a word of it. Sounds quite romantic if you don't know it's literal."
"If you could refrain from playing with fire, I'd appreciate it," Aziraphale says.
"Never," Crowley says, kissing the top of Aziraphale's head.
And so, that's how Aziraphale and Crowley spend a few years as man and wife.
Much later, they will exchange rings, and chalk the whole thing up as practice.