In Castiel's second appearance, he comments that he is a soldier of God, and does not perch on anyone's shoulder. If I'm not imagining things, he makes reference to the host of heaven, on several occasions, and their ongoing war against the legions of hell. In the Christian tradition heaven has an army, but there are lots of other things on their agenda. Angels are warriors, messengers, protectors and devoted worshipers of God. There are angels whose entire purpose is to praise God. There are angels who spend all their time delivering messages from God.
1. Is Supernatural's heaven just in total war mode, or is it really wholly given over to soldiering? The demons of hell clearly have purpose beyond releasing Lucifer from his prison, and bringing about the end days - overwhelmingly, demons seem to be interested in causing pain for pain's sake. Do Supernatural's angels have a similar side gig?
The heavenly host: the army of heaven. Distinct from the larger angelic hierarchy, which includes angels devoted to helping humans in various ways, angels devoted to praising God, and angels devoted to passing along God's word to the other angels.
The legions of hell: the army of hell. Again, it seems to be distinct from a larger demonic hierarchy. And there appear to be about equal numbers of angels and demons.
On SPN we only ever get mention of the host, and not any other heavenly activities. We do get to see more than the legions of hell, though. There are plenty of demons who are uninterested in world-conquering, who just want to raise a little hell, as it were. Can we take it as read that the angels mirror demons in this way - are there non-soldier angels out there, doing their thing? So far there's no proof either way, but I'd like to think that the angels have something to occupy their time other than waiting for the next apocalypse to break out.
And whether the angels are all soldiers, or there are non-soldier angels still up there, what did all the soldiers do before Lucifer rebelled? Was Zachariah always middle management? What did Uriel do before he had towns of mud-monkeys to smite? The angels can't always have been warriors, because there wasn't always a war to be fought. Presumably Supernatural's heaven, before Lucifer's rebellion, was overall pretty harmonious. Some estimates place the number of angels in heaven at one million - what did SPN's absentee God need with one million warrior angels, with no war for them to fight?
Once Lucifer rebelled, and the war started, the angels went from doing ~whatever~ to being soldiers. If we assume that all of heaven is now preoccupied with fighting the war, then we've got a massive army of angels to conceptualize. Even if only a portion of the angels are fighting full time, there's still a command structure that the show hasn't done much to illuminate.
2. What is the command structure of the heavenly host? Who are the big boys, who've taken over heaven?
What we know from SPN: angels are organized into units called garrisons. These units are made up of ordinary soldier-angels, and specialists (like Uriel). The command structure is much like that of a human army. There's a unit commander, with a commander above him/her, and another above him/her. Archangels are heaven's deadliest weapon, and are in a special unit - they operate alone, and are not part of a garrison. They also have high rank.
I think it's safe to assume that at one point, Castiel had command over other angels (he was nominally in charge of Uriel, frex). It's not clear how many he was in charge of - was he the angelic equivalent of a lieutenant? A captain? A major? When he is demoted for thought crimes, he seems to hold rank equal to, or below that of the specialist Uriel. He spends a lot of time being brought to heel by Zachariah, in a rather humiliating fashion. I think we're meant to assume that Castiel was demoted, and then demoted again, before he finally rebelled - that's two bumps down the chain of command.
What is Zachariah's rank? I get the impression that he's not the commander of Castiel and Uriel's garrison. He seems to view Castiel as a distant inferior - he's clearly a lot higher up the chain of command. His experience with the earth, and with humanity is also clearly different. He's more comfortable imitating human mannerisms, and much more comfortable with independent thought. Zachariah isn't an archangel, but he's clearly powerful, both in terms of his abilities, and in terms of authority. Zachariah is a big picture angel, and has been for some time - has this always been the case?
Can one advance in the angelic hierarchy? Or just move down when you screw up?
3. Which brings me to another question, what is the nature of angelic power?
When the future!angels take off to parts unknown, Castiel 'goes mortal'. He doesn't say that he's become human. He says that he's become mortal. Going mortal means losing his angelic powers. It seems to be distinct from falling and being reborn as human. Are human!Anna and mortal!Castiel essentially the same sort of creature, or is there in fact a difference? I'm going to come down on the side of there being a difference, because Castiel is not human, cannot be human, unless he loses his grace. With his grace intact but diminished, he's still essentially an angel. Recharge his grace, and he's an angel again. Human!Anna, in contrast, had to locate and consume her grace - it was a transformational process.
There's further evidence of my charged/uncharged grace theory: Castiel's separation from heaven, post rebellion, has also clearly diminished his powers. He can't heal Bobby, frex. It seems that angelic power, flows from heaven. Cast out from heaven, and from the host, Castiel is still an angel, with serious supernatural mojo, but certain things are just beyond him. So it seems that angels have some level of innate power, so long as other angels and heaven exist, as a power source. Once they ~go away~ angels who've taken human vessels, become like humans. One wonders what happens to angels who haven't taken vessels. :/
However, there's an exception: archangels. Lucifer seems to have retained all of his angelic powers, despite having been cast out (ie. separated from the angelic power source). There is something about archangels' nature, that makes them fundamentally different from other angels. While Castiel was able to reconstruct Dean, after his body died and began to rot, once he's effectively cast out, he can't even heal Bobby's spine - that's a huge difference in power. Lucifer though, says that he is fully able to resurrect Sam, despite his having been cast out. He can even reconstruct other angels (as per Raphael, his fellow archangel).
There's also the matter of angelic ritual and craft to consider. Angels seem to possess some inborn powers (teleportation, manipulation of time, exorcism, dream walking...), but they also supplement their powers with what looks a lot like magic. They've got rituals to summon and banish angels. Symbols to block angelic and demon perception. And what else? It's interesting that Castiel and Anna have been particularly associated with angel magic, while Uriel and Zachariah seem to rely more on their in-built powers. (Or not in-built, but rather the powers that flow from proximity to heaven/God).
4. So if angelic power is... flexible, excepting archangels, what does that say about rank in the host, and in the wider hierarchy? Just what kind of angels are the characters we've been introduced to?
If we go by the Christian tradition, I'm going to peg Zachariah as something like a Dominion: he's not one of the angels closest to God, but nor is he a foot soldier. He's effectively heavenly middle management. Castiel and Uriel seem to be either be Powers or run of the mill angels. Powers are described as keepers of history, and as warriors totally loyal to God. This describes Castiel and Uriel to a tee (before we know about Uriel's duplicity). I don't think that either of them is supposed to be the lowest class of angel, or at least not among the least powerful. Uriel is a certified BAMF and while Castiel doesn't exactly do well in most of his fights, he dispatches his fellow angels pretty darn efficiently in 5.01. I think it's bad writing that casts him as a poor fighter, more than deliberate characterization - rather than Castiel being a poor fighter, I think Alastair and Uriel were just supposed to be that damn awesome.
If Supernatural has non-soldier angels, then it's obvious that the characters we've been introduced to so far, are not among their number. Uriel, Zachariah and Castiel are all intimately involved in the war effort. Anna would have been too, had she not chosen to fall. In SPN, where no angels have been on earth for 2000 years, any contact between heaven and earth must come in the form of watching, dream-walking, gleaning stuff from the work of prophets, or direct revelation to particular individuals. Castiel manifestly is not an angel used to, or comfortable with human contact. He takes an interest in humanity from early on, and quickly finds things about them and the world that he likes, but he's no messenger angel. He's an unquestioning (mostly) soldier of God. Castiel doesn't even seem entirely comfortable in the task given to him (ie. Dean) - he's not used to keeping humans on track, to guiding them, or even to protecting them. It's not his regular gig.
This is either evidence that heaven has no perch-type angels available, or that the heavenly host didn't want the ordinary angels involved in what is some serious business - guiding Michael's vessel towards accepting his fate.
5. Which brings me to my last question, how much did Castiel know, and when did he know it?
Zachariah doesn't trust Castiel, and hasn't trusted him for some time. Not only is Castiel tainted by this doubts, there's the sense that he's just a hammer, to Zachariah especially. So how much of the plan did he know in Lazarus Rising? How much in When the Levee Breaks? I'm not sure there's any clear evidence, but I'm leaning to: not as much as he would have liked, but more than we will.
The trend has been toward Castiel being a little more culpable, a little more involved, than is comfortable for a viewer who wants to unreservedly love him. He's been willing to do some pretty disturbing things (from our pov), and probably still is, simply because, he's not human, and has never lived in anything like a human society. He doesn't think at all like we do, and he doesn't value human life like we do. That's not to say that he doesn't value human life full stop - he values it for different reasons, and in different ways. He is now invested in protecting humanity as a whole, and particular individuals (although who knows - he might be completely willing to sacrifice Bobby and Sam, even now), but he doesn't necessarily see any reason to spend time protecting individual humans.
Castiel has been booted out of the angel club, but he hasn't gone mortal yet, either in truth, or in terms of his thinking. He's still thinking like an angel - just a rebel angel. I have to wonder, will there be further revelations about his actions? Is he hiding anything else from the Winchesters?
Anyway, this post was more about asking questions than answering them, so I'd love to hear your answers to the above.