Imagine, after watching or reading Good Omens, that someone leaps out of the shadows and asks in an academic sort of voice, "Tell me, good sir (or ma'am or being), which is the bold, independent dominating care-for-nothing, and which is the insecure, needy, hesitant follower looking for a warm, reassuring relationship?"
I suspect the first knee-jerk inclination for many would be to say, "Oh, I didn't know this was a seminar, but all right: Crowley's the care-for-naught, and Aziraphale's the insecure follower." I mean, it's obvious right? Gentle, meek, fretful, worried Aziraphale with his prim clothes and his fine manners and his overall *goodness,* and his radiant, glowing crush on Crowley, and Crowley with his swagger and his sarky glowers and his flambouyant cover persona, and all that? And it's Crowley who seduces his Angel into the Arrangement, and who outright pleads for his alliance resisting Heaven and Hell and the Apocalypse itself, right? "Leader," right?
I'd argue otherwise. (But you saw that coming, amIright?)
I'd argue that the entire relationship and the nature of the two characters is writ bold in that first sequence on top of the wall of the Garden.
Think about it. There is Aziraphale. He's standing his watch, he's where he was posted. He's head up and eyes forward--alone. Not seeking company. This in spite of the fact that he has done the unthinkable, knowing on some level that he's exceeded his angelic writ. He's given Adam and Eve help and succor, provided them with a way out of the Garden that it appears God had not planned, and he's given away his flaming sword to help them. He's already pretty sure this is not *technically* the Great Plan: the WRITTEN plan. His only loophole is the Ineffable Plan, and by its nature that's not a sure thing. But...
Aziraphale, standing alone on the battlement, staring fretfully into eternity, has done what he believes was right, even if it was not what God wanted. He is not seeking solace (though, yes, he's bloody relieved when some shows up on slithering scales). He is not praying to God for reassurance. He's not even doubting his fundamental sense that you do not send two blithering innocent *babies* out into the cold dessert night, one of the two knocked up, neither with a clue about much beyond the basics of a fruitarian diet. It's not right. He's not shocked that God does not appear to know this: he's *worried* that God does not appear to know this. Here it is, the dawn of time, and he's already got a rather mournful grip on the contradictory relationship between God and Good.
Now, here comes Crawly, softly, softly, on serpent scales slithering. It's been no easy squirm up the wall of the Garden. Long way up a fairly sheer vertical incline, all to find the figure perched up on the battlement. Crawly is looking for company. Crawly is looking for reassurance, and, yes, he knows that Hell is no place to look for reassurance. He's done what he was told--and he's got second thoughts.
Frankly, he's got second thoughts about the entire mess. It doesn't add up, and he's unhappy, because he's got an imagination, and his imagination tells him that "Good" is supposed to mean something *good.* And this doesn't seem to tally up with what's going on.
The tree--it really was a bit panto. And how do you expect a couple of babies like that to resist temptation and do the right thing when the entire point of the tree-stuff is that they do not KNOW right from wrong? God didn't put that part in! Two babies without a clue, with no sense of good and evil--and you set them a test to see if they refuse to do evil when tempted? Bugger that for a lark! What's God doing playing silly buggers like that? And--his own role. Go up and make trouble. So he does a bit of tempting and damned if it doesn't feel like he's been suckered into playing the patsy in a game of God's devising. Did he do something good, because he did God's will? Or good because he obeyed Hell's command? Or bad because he tempted Eve?
What good is obedience when it just lands you in moral quandries?
Crawly, the obedient servant; Crawly, the insecure; Crawly, the lonely; Crawly, the hesitant, is looking for company and reassurance and someone to act as a backboard to toss his disturbing ideas against. Crawly needs some help, here, and he'll climb every mountain, ford every stream, and creep his way up the wall of the garden to find someone who will listen to him, even if it is an angel.
If that were not enough--that divergence in character brought up from the first instance of the sequence--there is the end, in which the rains come down, and without even a moment's hesitation on either side, Aziraphale does as no angel ought to do, and stretches out his wing to shelter Crawly--and Crawly, again without hesitation, moves closer to accept that protection.
It plays out over the entire story. Aziraphale, come what may, thinks for himself. He reaches his own conclusions. He can be convinced--Crowley often convinces him. But he can also stand firm--in the face of his beloved demon and in the face of Gabriel and in the face of all Heaven. He is what he is: the Angel of the Eastern Wall, who gave away his sword in the very dawn of time, because it was the right thing to do.
Over and over, Crowley is surprised by Heaven's quixotic violence and evil. "What-the kids, too?" He's shocked at how blood-minded God and Heaven can be, and he's not comforted by ineffable hopes. He's surprised. Imagination or no imagination, he has a hard time doubting God or Hell. He takes them at face value until they ram it down his throat, over and over, that they're not all they want you to think they are.
Aziraphale is not surprised. On some level he has known since we first see him that there's something amiss in the formula. He comforts himself with ineffability, because it offers him his only moral way out of the dilemma. He agonizes over his proper role--but that's because he knows that when his moral understanding conflicts with what appears to be God's will, he will follow his own conscience, and that's not supposed to be his nature. But he'll do it, and he won't go running to God asking forgiveness, or go looking for a human or demon or other angel to absolve him.
Aziraphale is the stronger one--and he's the one Crowley can't imagine acting without. Got a problem? Go talk to Aziraphale. Ask for Aziraphale's help. Lonely? Go tease Aziraphale. Uncertain about something? Double check it with Angel.
Crowley is melodramatic. He's flamboyant. He's Katherine Hepburn swanning around creation burning up the stage and sucking the air from every scene he can. But...oh, my dears, BUT...
Aziraphale is an unexpected, prim, neatly dressed Spence. Capable of worry, uncertain sometimes, but the rock and the foundation upon which Crowley depends. The bold one who chooses an action and stands by it, silent, on top of the wall. The one who gives away the flaming sword. The one who gives his heart to creation before Crowley does, because it's cold and there are dangerous animals and she's already expecting and it's just WRONG to send those two infants out without so much as a sword to defend themselves and a bit of fire to light the night. Because Aziraphale is secure in his own intuitions of good and evil. He may fret, he may doubt--but he does what he does, and there's no sign he actually regrets it--just fears the consequences and the logical conclusions.
Of the two, it is Aziraphale who most resists the orders of the Boss. Crowley comes to it, first evading orders through the Arrangement, and then trying to loophole through them as Apocalypse threatens his comfy little world, and finally at the end joining with Crowley to defy Satan himself defending Adam. But Aziraphale defies God's will from the very first, no matter how he frets about whether angels can do evil and how they're supposed to obey orders. That only makes his recurrent choices the more amazing.
Aziraphale's entire arc with Crowley's request for Holy Water weaves into this, somehow. But I'm still brooding about it. The important element is his own belief that Crowley is looking for a suicide pill--a possibility that is never really ruled out, even when Crowley uses it as he does, to kill Ligur and bluff Hastur. Crowley has come to his friend for cyanide...maybe. (Honestly, given his entire demeanor, I am inclined to think that Aziraphale is right, and no matter what Crowley is telling himself, he's ALSO counting on the Holy Water as his cyanide pill.) Watching Aziraphale squirm and writhe through that request, and through his eventual gift, is...interesting, not least because it's not obvious. It's the love for Crowley, following the Germans-in-Church thing, (dear, dear, darling Mark Gatiss!), that forces Aziraphale to give his friend the gift he least wants to give him: access to utter death. But it's also love for Crowley that forces him to say that Crowley goes too fast for him: Crowley will be the death of himself, and Aziraphale can't yet go there.
Which does lead to one final comment. Aziraphale, sadly, fearfully, at great emotional cost, accepts that his friend may kill himself...and loves him still, while providing the suicide pill. Crowley has a harder time accepting his Angel has been killed--and I doubt he would have as easily given his Angel the means to accomplish his own destruction.
So--Aziraphale, to me, is the "strong one." The bold one. The one who clearly deviates from his set role and his obvious stereotypical attributes, to stand alone and confident of his own standards and beliefs. Crowley, to me, is the one who wants company, wants social contact, wants a friend, wants someone to talk to. He's the one who proposes the Arrangment, one suspects as much for the excuse to go visit Aziraphale as anything. It's Crowley who reliably pops in, after all, looking for a bit of company. Aziraphale likes company--and when he spots the demon is happy to offer a dinner out. But he doesn't go looking for the demon in the same way that the demon looks for his Angel.