I Would Be Your Slave

Aziraphale makes one temptation too many under the Arrangement, and is condemned to be the property of Hell.

Crowley has millennia worth of soul credits unspent, enough to purchase an enslaved angel.

So that's all right, then. Quite a good thing, really. No one can object to them being together if Aziraphale is officially Crowley's property. Once Aziraphale gets used to the whole slave thing and remembers Crowley would never, ever harm him, he'll realise it's all for the best, that Crowley is his saviour and liberator. They can have the kind of happily ever after Crowley always dreamed about. It's a shame about Aziraphale's powers, but Aziraphale will understand eventually, especially when he realises how much Crowley loves him and always has.

It will be fine.