Last warning, here’s my initial bullet point. Maybe I’ll add more as I continue rewatching both shows:
First off it’s already established in TMA that the north americans are out there hunting, and it’s established in Supernatural that the british are out there forming an academic institution to study the supernatural. Yes the names are different but walk with me.
Dean as an avatar of the Hunt, obviously. He’s died enough to become fully an avatar at any poiny honestly. I could see Sam as just being marked by the Corruption but I like the idea of him becoming an avatar of it after he died on season 2. Maybe the Corruption got tired of him and he started fully servinf the Hunt after season 5?
Listen. Hell is a plane of the Desolation, Purgatory is of the Hunt obviously, the Void is the Lonely. What about Heaven? I honestly feel like it’s the Web or maybe the Spiral. God isn’t actually the creation God but an entity of the Web. Think about it. Being from a higher dimension that has planned every single thing in your life to accomplish reasons that escape your comprehension (and in both cases those reasons are the entertainment of us the audience!!). The way Supernatural presents Heaven does not seem heavenly at all, but more like being trapped in a web of happy memories that ensures you’ll never want to escape. And the concept of a plane made out of millions of separate rooms that go on and on for eternity but are always the same just reminds me a lot of the Distortion, plus the deceit and messing with perception of it all.
So every character in Supernatural that we see in either of those planes after they die we simply just snatched by the corresponding entity, everyone else is just going wherever the End takes you. This would also explain why main characters are brought back seemingly easily but it’s not possible for others.
Sam’s stabbing in s2 for example would be an actual death though (and we never see what his soul was doing those few days) because to become an avatar you do have to die and be born again as something Different. Azazel even makes a reference to Sam having come back not being fully himself in the s2 finale!
The angels pose a little bit of a problem because while a lot of them are bad and acting as agents of the Web, some like Castiel end up being good or neutral, straying from their function of making the Great Plan stay on course. In TMA everything supernatural or fundamentally non-human is out to get you and very much Not Friendly.
But I’ll say that the same way that our dear Jonathan can fall in love or that Hellen can decide it wants to fujoshi out and try to help in its own twisted way, an aspect of the Web like Castiel can decide it wants to kill its own kin and trail along with two avatars of the Hunt. To be fair, Castiel doing that did help make the show more entertaining so how can we know his rebellion wasn’t part of the Web’s plans as well?
I do also like the idea of Castiel and other angels having elements of the Vast, but tbf the angel’s abilities, traits and motivations are simply whatever the plot needs at any given moment. Yes Castiel is the size of the Chrysler building but the inmensity of what he is (enough to make demons terrified in Lazarus’ Rising!) is not used enough in practice to be a prominent part of what makes him scary, I think
Azazel is the corruption but also the Desolation. Fire, destroyed potential, the certainty that it didn’t have to be like this you could have been a normal family none of this has to happen but it did, and you can’t stop it from happening over and over again. Or whatever