Thanks for a fantastic question, anon! The evidence I’ve put forward for this characterization of Crowley comes directly from the novel; I think this may even be the second or third time I’ve received this question. As I’m currently at work and don’t have access to either my e-book or one of my hardback copies, I’m going to give you a list of items and quotes from canon, off the top of my head, that point in this direction:
- In the Beginning, Crowley makes a beautifully foreshadowing remark to Aziraphale: Funny if we both got it wrong, eh? Funny if I did the good thing and you did the bad one, eh? Pay attention to that sentiment next time you reread; all following instances of Crowley doing the right thing and Aziraphale doing the wrong thing thereafter will seem starkly obvious.
- During the series of conversations that led up to the Arrangement, Crowley is the first one to bring up how unfair humans have it, that you can’t expect Aziraphale’s (read: Heaven’s) idea that humans are only good or bad because they want to be to work unless you start everyone off equal (You can’t start someone off in a muddy shack in the middle of a war zone and expect them to do as well as someone born in a castle, he says). He finds Heaven’s lack of mercy deplorable (That’s lunatic, he tells Aziraphale).
- Aziraphale is too careless to take a living dove’s welfare into account when he shoves it up his sleeve in the first place. When he finds it dead and squishy in his coat, he’s no more than mildly annoyed; Crowley, on the other hand, gently takes the bird from him and breathes life back into it. Actions speak louder than words.
- Crowley’s reaction to the Spanish Inquisition breaks my heart, i.e. once he hears about the atrocities, he goes and gets drunk for a week in order to forget. Compare this reaction to one of the fleeting thoughts he has while he’s on the M25, having just left the scene of Aziraphale’s burning bookshop (and I need not quote you fragments of that scene from memory, although I swear I’d do it if I thought it were necessary to make the point): Aziraphale’s gone, the world’s going to end, so why not find a nice little restaurant somewhere and just get drunk out of his mind? That’s so very, very telling.
- Early in the book, the narrative makes light of Crowley’s dislike of the fourteenth century, but we find out later, in a moment of extreme terror and duress, that he hadn’t felt like this since the fourteenth century. I’m a scholar of the Middle Ages, so for those of you not intimately familiar with the fourteenth century, I’ll tell you this much: it was a vibrant, fascinating, brilliant time to be alive. Someone like Crowley would not have found the fourteenth century dull. No: for my money, he spent the latter half of the fourteenth century terrified because that’s when the Black Death ravaged Europe. All of the things you love in the world, humans and all their brightest achievements, snuffed out by the millions. That’s so vast that trying to drink your way through it would’ve been unfeasible even for an ethereal creature like Crowley.
- Crowley’s boundless optimism, never mind that he’s completely and utterly terrified of his employers. Think of his reaction every time they contact him over the radio or cutting into what he’s watching on telly. You cannot convince me that someone whose Fall is pointedly described as just sauntering vaguely downwards is actually evil. He sides with an angel and humanity and successfully helps them to win a rebellion using only words and ideas.
Crowley’s core nature is writ large on every page, as far as I’m concerned. If you ever reread the book, I’d be interested to know if you reach a similar conclusion.
And of course there’s Aziraphale’s belief that Crowley is unable to feel or even understand love/goodness. From the examples above, it’s obvious that Crowley’s capable of empathy, but Aziraphale’s callousness toward him, and his detached relationship with humanity, even after 6,000 years, proves that empathy isn’t one of his greatest virtues.
What they’re able to teach each other is such an incredible inversion of stereotypical expectations, too: Aziraphale shows Crowley what it means to be ruthless when push comes to shove, and Crowley teaches Aziraphale a thing or two about mercy.
Although, just going to say, he is essentially kind. One of the first things we learn about Aziraphale is that he’s given away his flaming sword to Adam and Eve because it’s cold and she’s expecting.