Death watches. He watches everyone all the time; including and especially the immortals, because they tend to die more often than everyone else and need someone to help them shed their moral bodies. When it happens, Crowley usually scowls at him, but Aziraphale is always very polite. It's really too bad, Death thinks, that this time it's going to be Crowley.
Hastur and Ligur have been trying, rather unsuccessfully, to kill Crowley for months. Lucifer has ruled him untouchable, so they can't act directly, but they really would like a word with him back in hell and the only sure-fire way to get him there is to use intermediaries to destroy his current corporation. Unfortunately, the IRA suicide bomber hit the wrong block of Mayfair flats, the hired hit man couldn't pick out just one flash bastard in a dark suit and sunglasses and ended up taking out an entire bank before the police captured him, and on that hopeful day when the dukes dressed as farmers and asked a priest to bless the rain clouds for them before running off as quickly as possible, Crowley stayed in, watching old movies and drinking cocoa.
They refuse to give up, though, which is why they are working out a deal with Pestilence.
Crowley and Aziraphale are dining at an intimate Indian restaurant in Soho. Well, Aziraphale is dining. Crowley is pushing his vegetable korma around the plate and watching his naan drown in the dal. Aziraphale looks up with concern writ in his light eyes.
"Are you quite all right, my dear? You look terribly pale."
"I'm just tired," he says with a frown and coughs.
Later, when he stands to leave, his legs give out and he falls to his knees. Slightly dazed, he tries to stand again but the angel won't let him. Aziraphale throws too much money on the table, picks up the demon, and miracles them both back to his shop. He tucks Crowley into his mostly unused bed and brings him a cup of tea. They don't talk then. Aziraphale just leaves him to his rest.
It takes a week or two of Crowley living in Aziraphale's flat for them to realize what is wrong. Consumption, Aziraphale calls it, but Crowley prefers the medical term - tuberculosis. Both of them try to heal him, but somehow it is miracle resistant. The angel takes him to hospital, but it's resistant to all human medicine as well, so he brings him home again. They both realize this is too convenient to not be a deliberate attack. They never discuss it.
Instead, Aziraphale adds caring for Crowley to his daily routine. The demon is not a petulant patient. He does little but sleep and drink tea and cough blood. Aziraphale works during the day, thwarting entirely human wiles and running the shop, but all night, every night, he stays with Crowley. Usually he reads to him. It doesn't matter if the demon is asleep or not because the sound of Aziraphale's voice calms both of them.
There isn't much in the shop anymore that would interest Crowley, or any adult really, but Aziraphale finds a book of Norwegian folk tales. They both enjoy the stories of terrible trolls and humans transforming into bears; of beautiful princesses who are treated cruelly but remain gentle and kind which endears the trees and the animals to rescue them; and of poor but clever young men who perform tasks in threes in order to secure fame, riches, and the hands of the beautiful princesses. And all the time, Crowley is getting paler and thinner like the princesses from the book, snow white skin and rose red blood.
The end is near and they both know it. Aziraphale is almost relieved because soon he will be free of pain. Crowley doesn't want to leave. He knows what awaits him down below.
"I'll be back soon," he says. "I won't be gone long."
Aziraphale says nothing but brushes a sweat damp lock of hair off Crowley's forehead.
"I love you, you know," Crowley whispers, gold eyes fever bright.
"I know, my dear. I love you, too."
"I know."
There is no mashing of lips or fumbling for clothes at this declaration. They are not designed for sex and have no desire for it. They are perfectly content to simply be together, fingers entwined. When Crowley's eyes close, Aziraphale's do, too, and his shoulders shake with suppressed sobs. He is not naïve. He knows what awaits Crowley, too.
Death watches, but he is not the only one. He knows his duty has been taken from him and he turns to see a golden haired boy smiling at him. The boy reaches up to pat a fleshless shoulder blade.
"Sorry, 'bout that. But I just couldn't. Take you for a cream bun?"
Death grins back, although honestly it would be hard for him to do anything else. "YES. THAT WILL BE ACCEPTABLE."
And as Adam and Death are sitting down in a tea shop, a demon in Soho is sitting up and an angel is crying and praying and laughing all at the same time.