like aziraphale, michael tried to fix heaven in their own way. the book of life allowed them to see every possible timeline, every choice that could have been made, what did and didn't happen. no one (including celestials) is meant to know all of that at once.
it very much reminds me of rose tyler looking into the heart of the tardis and becoming the bad wolf, with the doctor having to sacrifice himself to save her. while she had that knowledge, that power, she made jack immortal, she manipulated the very fabric of reality even though she shouldn't have.
michael did something similar, changing small things at first, and the book compensated. erasing the metatron didn't do much, and murdering sandalphon didn't either. even getting rid of uriel didn't destabilize the universe. my point is, there was no external reason for michael to start burning everything down.
what they saw, every single possible lifetime of the universe, led them to the conclusion that they cannot fix heaven. they cannot fix anything.
everything they might have tried did not change the story because it was already written.
before, the celestials did not know that. they were meant to blindly follow orders, to trust in god's Great Plan without questions, which includes the demons. armageddon, the antichrist, the second coming—every apocalypse was built on expectations, but they never knew for sure.
god is the only one who knows what game they're playing and what the rules are, and it's not chess, there are no pawns. azirphale comparing it to solitaire is really what it comes down to. there is one person playing, one person who can win, one who controls every single card and even shuffled the deck. the cards themselves do not have the power to change the game. once the game is done, everything will be destroyed because it has fulfilled its purpose.
season 1 and 2 showed us that many celestials are uncertain of what's meant to happen, they follow orders, and crowley and aziraphale tried their best to save the world within the limitations outlined by god and the prophecies.
problem is, they knew even then that there's a non-zero chance they were supposed to prevent armageddon. god's plan is ineffable, after all. who's to say that their roles aren't written into the book? how can they actually tell if they have free will or are just doing what god created them to do?
the starmaker is told that after six thousand years, the universe will be destroyed. not just earth, every single star and planet and nebula and galaxy. creation as a whole will be undone, the curtain drops, that's it.
no one knows what that will look like, but they all know it will happen, so they have to trust that god has a plan for them. otherwise they'd go fucking nuts, which brings us all the way back to michael.
the illusion of free will and agency disappears when working with the book of life. is anyone free to do as they please when every possible action has been predicted in advance? how is michael supposed to have faith in god when confronted with the reality of their situation?
even satan is not free, he's a villain of her own making, he rebels the way he's supposed to. they all fall not because of their actions or because they're "evil" or bad or demonic but because that is how the story goes. in the end, aziraphale understands that, he understands that crowley was never evil, they were never opposites. there was no sensible purpose to anything.
so michael does the only thing they CAN do, the most free choice there is: they burn it all down. maybe that was meant to happen, maybe it wasn't. maybe it was their first true act of free will, and they used it to get rid of the literal and metaphorical book.
so what exactly are crowley and aziraphale meant to do?
put everything back the way it was? then what? angels and demons still want to go to war, humans are still being tortured in hell, the universe is still being manipulated behind the scenes; by god or by them, it comes down to the same result.
the last thing crowley wants is to become like her. he fights for his agency, he questions her even as she is about to destroy them. why does she get to make this choice? why is everything always up to her?
there's no real answer to that question, so god gives him an offer instead: you get one choice, one act of free will, do with it what you like.
so he does. he doesn't need the book of life to understand the reality of their situation, he's known for thousands of years. michael burned it all down, but he wants something to come out of this. there needs to be a reason for all of this, a consequence, something that actually matters.
burn it all down, yes, and then plant a new seed. water it, let it grow, but don't you dare touch it. its purpose is to exist and nothing else, a universe with genuine free will.
i understand how the ending can seem depressing, but personally i do not find it nihilistic or see it as an act of defeat. everything they did mattered, they're the fabric of the new universe, their love the big bang.
sometimes, you cannot fix the system. sometimes you have to tear the house down and rebuild it from its ashes. there's sadness and grief, but it still happened, it mattered.
the love will always be there even when you can't see it.
