(a meta, or maybe I just need to lie down and stop overthinking everything)
So it’s been made clear that the sunglasses aren’t going be treated in the same way in the tv series that they are in the novel by this point; in the novel, Crowley is only described to have his eyes on display once - when they’re knocked off his face by a jet of water in the burning bookshop, and he almost immediately creates another pair after this happens, whilst in the tv series, already we have seen his eyes on five separate occasions. 1) In Eden (obviously), 2) in the bookshop when the two of them are drunk (this was from a sc master_crowley posted, from what little I could tell it is in the bookshop and Crowley has his 2007 long hair), 3) when he faces off against hastur and ligur in his flat, 4) when he takes them off outside the burning bookshop, and 5) he doesn’t appear to be wearing them at all throughout the final act at the airbase. The only real reason I can think of as to why they chose to make this change, other than David Tennant With Cool Snake Eyes Hot And We Need To Show It Off As Much As Possible, is that the act of Crowley wearing and/or taking off the sunglasses is somewhat symbolic.
I believe that the sunglasses are symbolic in that they represent the image Crowley presents himself as - suave, cool, apathetic, and loyal to his respective head office. They’re a symbol of who is trying to be, and how he is trying to appear to other people. So, whether he is wearing them or not in a certain scene is supposed to tell us whether or not he is showing his true self and his true feelings. Namely: if Crowley is wearing his sunglasses, he’s putting up a front, and if he isn’t, he’s being his genuine self.
So, using the scenes we have so far as an example, Crowley doesn’t wear his sunglasses in his face off against the two demons in charge of him because he is no longer feigning loyalty to hell. At this point he has been discovered to be plotting against them to stop Armageddon, and no longer needs to pretend he’s on their side. But it’s the fact that, apart from this one, just about every other scene concerns aziraphale in some way, that leads me to believe this symbolism is the case.
In Eden, Crowley, instead of remaining a serpent like be does in the novel, shapeshifts into a man in order to speak to aziraphale. This scene is obviously very important: it establishes right off the bat that both crowley and aziraphale are somewhat of outsiders from the other angels and demons - their disillusionment with their respective sides and the overall system is what sets them apart from their own kind, and brings them together in the first place. You can seen Crowley’s eyes here because he’s being open with aziraphale about how he feels about God and the ineffable plan. And that openness is what allows aziraphale to be open, and they realise just how alike they really are.
Fast forwarding a while, crowley taking off his sunglasses when he’s drunk in aziraphale’s home and is trying to enlist him in his plan to stop Armageddon is really telling. I mean, they get super existential and philosophical here - crowley really bears his soul to aziraphale, tries to appeal to that part of aziraphale he tries so hard to pretend isn’t there, even though it what’s brought them together in the first place. Aziraphale, really, is the only person who knows what Crowley is really like, under all that faux confidence and his aloof pretty boy attitude - he’s just like him. They’re both selfish and too comfortable in their lives and love the earth more than anything, even though that’s something that Crowley would never ever admit, but aziraphale knows it anyway because crowley’s never tried to hide it from him - if there’s one person Crowley doesn’t have to keep up an image around, it’s aziraphale - and that ultimately is what convinces him to betray heaven.
And then….we get to the burning bookshop. Do I even need to explain how this symbolism fits here? I’m guessing not, but I think that the difference in how Crowley loses his sunglasses in the tv series compared to the novel is DEFINITELY significant. In the novel, he regains his sunglasses almost immediately after they are knocked off his face, whereas in the tv series, it appears to go down completely differently. I think his glasses will still be lost when he’s hit by the water, but he picks them back up, determined to salvage them, because despite everything else going wrong around him, he still has his pride, his image, his determined smile in the face of imminent defeat, only to realise they’ve half melted after landing in the flames, and as he stands outside the bookshop, taking in just how royally screwed he is in every possible way, he discards the glasses. Because what does it matter anymore, anyway? Aziraphale is gone, or is being punished, or has defected back to heaven’s side, or dead as far as he knows. As far as he knows now, he’s all alone and he’s going to lose. He’s just walked out of a blazing bookshop that’s collapsed down on him completely unharmed with an entire crowd of people watching him, who is he trying to fool anymore? In this moment, Crowley is no longer the man in the image he has painted for himself over the last 6000 years. He is a demon, and he’s going to die today. No need to hide it anymore. And then he jumps into his Bentley, drives straight onto the M25 and spends the next few hours nonchalantly holding together his burning car through sheer force of will to the point where his eyes turn red with the effort, not a care in the world who sees.
From this point, I don’t think we’ll see Crowley’s sunglasses again, at least until the epilogue (if there is one). He has no need to maintain a facade anymore, at least until the world is saved and he can go back to living his comfy life as a human again. And honestly, if this is the case and I’m not looking too deep into it, which I definitely am, wouldn’t it be so much more magical to see Crowley’s reaction to aziraphale’s confession at the end, when he takes his hand and they walk to their deaths together, with his eyes exposed, when he’s at his most vulnerable, and most authentically himself? No walls or lies between them, nothing holding crowley back from returning the gesture, just acceptance, solace in the fact that he has nothing left to lose but the one person who truly understood him and saw past it all, and maybe dying isn’t so bad after all if he’s going to die hand in hand with them? Because in the end, if you’re going to go, it’s not about going out in style. It’s about going out in your own true shape.