Disclaimer: I don't own Good Omens in any of its incarnations. Duh. It'd have 900% more angst otherwise. A.N- For the prompt "Tragedy" from the Good Omens Celebration.
Lesson learned
Who bothers knowing Aziraphale? Crowley, for sure, and a few thousands people through the ages, for one reason or another. His angel brethren are absorbed in more important tasks, and God...she's a mystery. Knows everything, or so she says. But she doesn't always care, if the sheer fact he could lie to her face without consequences means anything. No one from that chosen crowd would be surprised to learn that the angel lived in the library of Alexandria for a while. Books and food are the two temptations he's always found the hardest to resist (if he bothered to at all), even back when volumes were literally rolled up, as per their Latin etymology.
All visitors to the city having to surrender their books to the library, and receiving a copy instead? That's so, so Aziraphale. Technically, it's so Ptolemy III. But he was a nice man, and could easily be talked into things when needed. Because sure, the angel started asking to just be allowed to have a look and miracling clones. But then - after an unduly harsh talking to by Gabriel about unnecessary use of their power - Aziraphale started doing it the human got a few people to help him out - and maybe that's why the whole Alexandrine literary style veered towards few words, carefully chosen. Big book, big evil...Callimachus resented the hours spent helping uphold Aziraphale's maybe slightly greedy plan way too much. Eventually, Ptolemy helped out, implementing the rule and shouldering the relative complaints.
Of course, as comfortably nested as the angel was in there, his little personal heaven had to end. They'd send him far away, wherever someone required a bit of a blessing. If he was to stay on Earth, he had to do his duty and keep in the thick of events, wherever - whatever might need a push to the light side. In the end, Michael had been the one to tell him in no uncertain terms that he had to move out or go back to actual heaven. Aziraphale's choice had not even been one, in the strictest sense of the term. Of course he'd stay here, wherever they wanted him. Earth had too many...lures to give up ( a certain demon included). Besides, he could always sneak back quickly every now and then.
Aziraphale still wonders, sometimes, if he's been too conspicuous. If this was meant to be a punishment for him, if someone else up in the ranks has an arrangement with the other side, or if just the residue of too many blessings, without an actual angelic presence, pissed off whatever demon must have been behind it. He knows it's not Crowley, and he's never asked. If he knew...the results wouldn't be pretty, and he wouldn't like himself afterwards anymore. But one day the library burns - and unlike all the other times, it doesn't pick itself back up (as far as the angel is concerned, Julius Caesar got what he deserved...he's still salty over these scrolls). In the grand scheme of things? It had already fallen so far from the days of its splendor. People, with or without demonic influence, have done way worse, before and after. But to him? It's a tragedy.
For the first time, Aziraphale envies Crowley, whose supervisors don't mind if he sleeps away a few decades. Oh well. He could sleep ages, and his lovely library wouldn't be any less destroyed when he'd wake up. He needs to keeps things small. Not attract attention. Lesson learned.