hmm, well i have to say from my own viewing perspective there is no such thing as a non-shipping point of view when it comes to their dynamic on screen—and i don’t mean that facetiously! because for me every moment of their friendship, every strain it endures, and affirmation it achieves, even if painted in an ostensibly platonic light on screen still contributes to their romantic potential for me, you know? that is to say Dean and Cas’ deep and convoluted friendship is the reason i ship Dean/Cas, so their friendship and romantic potential are more or less inextricable concepts for me. that is to say i am extremely biased as a disclaimer then, haha.
but yeah i think one of the things that makes their friendship so compelling, and indeed helps forge this ultimately unbreakable bond between them despite all their friction, is that they are remarkably similar in many respects, and i think that’s something Dean really holds onto. their issues with family, with authority, with establishing their own identities outside of that authority, it’s been a struggle for both of them, and one Dean has been able to witness first hand with Cas, and it’s been something that united them in solidarity even early on in their fraught acquaintance: “Can I tell you something if you promise not to tell another soul?”
i think Dean believes in Cas despite himself a lot of the time, but how do you deny the creature who very literally breathed life into you? who chose you, time and time again? Castiel has held pieces of Dean no other breathing being has ever seen. Dean is a man who hardly believes himself worth choosing—and Castiel, he did so many things in the name of Dean, he defied and he died and made so many mistakes, but then still, every time Dean lost him, he always came back.
i think Dean believes in Castiel because he goes beyond any expectation Dean holds for how the world works and for what he deserves. he’s an angel, untrustworthy, alien, but yet he became family. he’s betrayed Dean, but he’s saved Dean, too. he’s at once this paradox of a person who contributes to Dean’s sense of loss, to losing everyone he loves, but he also continually confounds it by coming back. he breaks Dean’s heart but in other ways he fixes it, he tells him “you can’t save everyone, my friend” but “thank you, for everything,” and means it with everything he is, this astonishing, unbelievable, bolt of lightning in a bottle that strikes through everything Dean thought was true.
in a way then maybe Dean believes in Cas because he shouldn’t, because faith is dangerous and friendship volatile as far as Dean’s concerned, in this life. but they defied every other rule of destiny together, what’s one more?