I know I've been promising my concluding mini-essay for weeks, but there are so much thoughts swarming in my head thanks to all of you that I have to shove a couple more chapters here before I am ready to tie all the loose ends and present my conclusion.
Once again I'd like to thank all of you who comment and drop me PM's, especially Blackamethyst, Elle4 and NorthernShinigami. You are great :)
Surely nobody doubts that there is a profound bond between Castiel and Dean. The question is whether sex or infatuation has anything to do with it. I will not try to argue that they reach the home run or enjoy horizontal hula on Impala's backseat. Nonetheless I will try to convince you that there is too much irrationality, self-centeredness and gut reactions that distort their perception for it to be mere friendship.
Like I wrote in my first mini-essay, Castiel loses his mind completely for Dean and perceives the problems he faces in ridiculously distorted proportions; up to the point when Dean's emotional blackmail drives him to self-immolation. I've covered the events of Season 4. Let's move on and consider Dean's attitude too.
In 5x18 Cas and Dean have their most heated argument. The angel makes mincemeat out of Dean for his decision to say yes to Michael. In her SPN thoughts Lurea suggests that Dean's decision to say yes is attributable to the need to protect Cas. I'd rather veer towards an opinion that Dean wants to protect Sammy, but that's not the point.
Castiel's reaction is very interesting. It's extremely emotional. Firstly, he laces into Dean by beating him nearly to death. Later... Well, he practically commits suicide.
When Sam, Dean and Cas break into the Green Room to save Adam, Cas goes in first with an angel banishing sigil carved on his chest to fix the guards. Before entering the shed he quite openly tells Dean that it will probably kill him, but he prefers death to watching Dean fall.
I know that the scene was designed mainly to salute fans with a badass shirtless Misha Collins moment, but let's focus on the plot for now and leave admiring the surprise-sexiness-and-badassery-popping-out-of-a-holy-tax-accountant aside.
Keep it in mind that Cas is not a regular angel. Earlier in the same episode we see him effortlessly finish off 2 angels that ambush him by Adam's grave. He does something funny with the angel blade and uses his left hand in fencing. I know the scene is lame and badly filmed (TBH all fighting scenes in SPN are lame), but the thing is that he is a skilled swordsman. He has the reflex, agility, strength, quick-thinking, clear-headedness and basically everything it takes to make him a great warrior. He is the guy angels chose to accomplish an impossible mission in Hell. While rescuing Dean Castiel commanded a garrison; he obviously led the charge medieval-knight-style rather than gave orders by a walkie-talkie from the safety of H.Q. It was his handprint on Dean's arm which means he was the first to break through to the Pit. Before he started to behave in a queer way, he had Uriel - the heaven's Tsar Bomb designed for leveling f*cking cities - on his leash. He's the John Rambo/Horatio Nelson of Heaven.
Of course trying to take 5 angels in a hand-to-hand combat would be risky, but he could at least try. Hell, Winchesters could try fixing some holy oil molotovs or pull another trick like they usually do. It was difficult, but manageable. Instead of simply trying to fight, Castiel chooses to go kamikaze. As it was not enough, he makes sure that Dean knows that he kills himself because Dean let him down. Aww, our sweet emotional blackmail and guilt-tripping.
If it was only about Castiel doubting that Dean could bear the burden of responsibility and help averting the Armageddon, the angel would probably try to find another solution. He would give up on Dean, but keep on trying to save the world in a different way. It is not the case. Cas gives up entirely because it is not the world that he cares about. It's Dean and only Dean. From the moment Castiel learns that Dean is just a broken and burnt out shell of a man - someone he cannot love - his life has no purpose.
In the whole performance Dean seems to be on the same page with Castiel. Whatever they have, it runs both ways. He is not shocked by Cas's hysterical behavior. He gets it. However unnatural and un-strategic it might seem, Dean is understands that the world ending, people dying and basically the most important moment of human history is somewhere in the background while what really matters is his relationship with the angel. He does not try to convince the angel to nut up and keep fighting. He understands that he has screwed up and broken Castiel's heart; that Cas has nothing to fight for anymore.
In 5x21 it turns out that kamikazing into the Green Room did not kill Castiel. It merely made him human. He wakes up in a hospital - wounded, confused, in pain. The first thing he does is calling Dean to apologize. The conversation begins with them talking about Castiel's situation and health, but it's Dean asking questions and Cas answering. The apology, though said by the end of the conversation, is the only thing Cas says on his own accord.
Another interesting proportion-distortion is demonstrated by the end of season 7/beginning of season 8.
From a bitter, but honest conversation Dean has with Emmanuel we learn that Castiel's betrayal is the only thing Dean can't stop thinking about. He's been to Hell, he's been forced to torture people. He's been lied to and betrayed by Sam. He was burdened with the awareness that his father went to Hell for him (and we know that Dean was not grateful for it, claiming that John did it for his own peace without thinking about emotional consequences for Dean). He started the Apocalypse. Generally he's been screwed over and hurt countless times in every way possible, but Cas's betrayal is the only thing he can't get over.
After regaining his memory Castiel decides to take Sam's hallucinations and pain to heal the younger Winchester and redeem himself. It's not enough to grant him Dean's forgiveness, even though Sammy is the center of Dean's universe and every deed for or against Sam grants Dean's gratitude or wrath tenfold. It isn't until that fateful conversation about being cursed that he finally opens himself to forgiveness.
There are two more moments that allow Dean to change his mind.
Firstly, the hunt for Dick Roman. There is a moment when Dick charges at Dean; Cas pushes the hunter back to cover him with his own body. Of course they had this wicked plan with a fake bone etc but Dean's confusion proves that Castiel's taking a blow for Dean was not a part of it.
Secondly, during their encounter in Purgatory Castiel reveals that he has turned himself into bait to lure Leviathans away from Dean.
These two deeds seal the deal. Dean is wholeheartedly pro-Cas again. Compared to taking Sam's torture these two risky situations meant very little, but it was what Dean needed to finally forgive Cas. He needed something that Cas would do only for him; excluding Sam from this balaclava sheet means something.
In 8x07 the tables turn. It is Castiel now who is rational, if only slightly. Dean is blinded by conflicted emotions. Castiel reveals that he stayed in Purgatory in order to do penance and that it wasn't Dean's responsibility to free him. He tries to teach Dean that he cannot burden himself with guilt and responsibility for every calamity. Admittedly he does it in a very unsympathetic, awkward way. Anyway, Dean pays no attention to the psychological guidance Castiel tries to offer. He is 100% focused on emotions. He nearly bursts into tears because Castiel ignored and hurt his feelings. There is zero rationality in Dean's reaction, though it is absolutely justified if we take the emotional angle. Cas reveals that he didn't take Dean's love into consideration; that he chose to stay in Purgatory even if it meant countless sleeples nights when Dean had to cry out his guilt, misery and longing. It is one of really few scenes where we see Dean fall apart. Again, this tough warrior who welcome the threat of Hell with a shrug is vulnerable to the pain Castiel is unknowingly inflicting on him. His eyes become misty, his chin twitches. It is a reaction of a helpless child that is about to burst into tears because it has no idea what is going on... all it knows it that it was hurt.
My point here is that the bond between Dean and Castiel is something else than friendship and that they both feel the same way. Friendship is rather rational and deliberate; it is based on correspondence of personalities and consistency of interests and outlooks. It could help people cooperate when completing a mission, but it would not obliterate their primary goals. Friendship has boundaries. Friendship does not make people that vulnerable or irrational. Friendship does not force people to forgive wrongdoings no matter the price. Friendship does not leave people shattered and confused. The relationship between Dean and Cas is based on something much more primeval, biological and instinctive; something that messes with their heads and overrides reason.
Of course Dean includes Cas in the family. The phrase family does not end with blood is one of the most important messages the show convey. But what is the nature of this familiar bond?
There is one other person whom Dean considers family. Bobby. The man who practically raised him and acted as a foster father. It took years to form the bond. It is based on care, gratitude and justified trust.
With Cas it took months to form the bond. It is based on... Well, it has no basis except for the fact that Dean and Cas apparently cannot live without each other. I'd even risk a statement that the bond is keeping them on a leash despite the fact that each of them would be better off without the other.
So they have a familiar relationship though they are not related by blood; a relationship that formed very quick and that is irrational, based on instincts and an irresistible, compelling attraction of whatever nature. Doesn't it sound a bit like a description of marriage?