Before I go on with any more of the SPN stuff, I should probably do the whole listing-of-ye-biases and meta-commentary thing. This is 145% opinion, speculation, and personal orneriness, and should not be taken as the basis of anything.

I was sort of aware of Supernatural before I started watching it. I hang out on the internets, after all. I had been told that Dean/Cas was a thing, although I had no idea who the hell they were at the time and I'd heard much more about the infamous "Wincest" people -- that happens to hit one of my personal squick buttons, and I was told it was prevalent, so I read no fanfic before I started prodding Netflix for episodes. I watched the first couple of season 1, then skipped to season 4, since I'd been specifically asked about Misha Collins.

I've been a fanficker for a long, long time. I write it (no, you can't see it), I read it (don't ask me for recs unless you want things that are slashy or interesting), and I study it (because I also cannot turn the sociology degree off). I respect the slash community and think they serve an increasingly vital function in a society that's still kind of lurching around the idea of less-than-rigid sexuality, but when I run into people who insist their same-sex pairing is genuine canon -- as opposed to people who operate as if their fanfic is in a plausible alternate universe -- 9 times out of every 10 I think they're somewhere between 'blinded by hope' and 'irredeemably bats'. Outside of things that are explicitly queer by genre, it's vanishingly rare, or at least it has been.

I confess that I've been unable to parse the relationship between Dean and Castiel as anything other than a romance from the end of season 4 onwards. Up until they were in the waiting room, I'd have reluctantly bought that Castiel desperately wanted a platonic Gemeinschaft connection with this man whom he had saved from the depths of Hell, but the conversation where Dean finally convinces him to join Team Free Will makes it look much deeper than that. At the first watch-through, I was unaware that the character of Castiel had effectively replaced Anna in a lot of the plot outline, or that Anna was originally supposed to be Dean's long-term love interest. If I saw two men acting like Dean and Cas do in real life, I'd start operating on the assumption that they were together, and not very good at being discreet about it.

I was also, at the time, unaware that one of the main showrunners and regular writers was Ben Edlund, who has a tendency to tell the Establishment to go fuck itself if he has a better idea for a story.

I don't know what's going on at the executive level of Warner Bros right now. I don't get to see the execs speak, and I can't evaluate how truthful they are, how uncomfortable the debate does or doesn't make them, or how much they agree with whatever statements are coming out of the studio. What I do get to see is the actors' work, and whatever they say in front of cameras in interviews and conventions. I'm satisfied that Jensen Ackles and Misha Collins, at the very least, are trying to build a "will they/won't they" relationship in which "they will" is genuinely an option. They have gotten so blatant I actually kind of wonder if there isn't some kind of tug-of-war going on over it, and having gotten an 'if it serves the story' brush-off, they are now trying to force the issue.

Castiel is odd no mater what perspective you're coming from, but there's a huge body of reasonably academic critique pointing out the many ways in which the character of Dean Winchester can be read as bisexual. Loads of links from here. Most (although not all) of what they point out are choices in body language and delivery that would have been entirely up to Ackles to develop in rehearsal. (TV shooting scripts don't have much in the way of stage directions. The writer doesn't know what the set will look like beforehand, or what the working environment will be like; typically the only actions noted are ones that are vital to the plot, and the actors and director are left to work everything else out when they do the first read-throughs.) I've seen several of them explicitly credited to Ackles -- particularly Dean's rom-com reaction to Aaron hitting on him in the bar -- and praised by the production team as brilliant. Other bits appear to have been the writers picking up on his subtext and writing accordingly. The script, for example, specifically gives Dean and only Dean a reaction shot when someone in Gabriel's faux-Japanese game show refers to Cas as a "pretty-boy angel". I wasn't aware of any of this when I drew the same conclusions, either -- I made it through a couple of seasons (and one trip to the Stop & Shop for pie) before I bothered poking the internet to see what other people were saying.

Both Collins and Ackles fucking impress me as actors. They both read very "true" -- in other words, the non-verbals they use are generally the same ones I'd key on in real life. (Not all actors do. I enjoy a lot who don't; it just depends on what they're doing and whether a more stylized approach fits. Nobody complains about a lack of realism in the Commedia dell'Arte.) I've seen Collins' personal analysis of what's going on re: Cas in season 4, and that's all exactly what I read off of it when I saw it. He is clearly quite good at getting these things out of his head and onto videotape in a format that I can parse accurately. His Castiel reads to me like he wants very much to be physically and emotionally close to Dean, to the point that the only thing that trumps it is concern for Dean's own safety.

The bits that I'm picking up on in-character are not actor bleed-through. Collins and Ackles are kind of all over each other IRL, but they don't do the things I would point to as what makes me think they're trying to establish attraction in the show. They do a great deal with silent eye contact when they're up to one of their impromptu comedy routines, which is a thing you see in happy married couples a lot, but you also see in siblings and very close friends -- it is distinctly different from the way they behave while in-character. Dean, for one, does an awful lot of staring at Castiel's mouth for someone who theoretically doesn't want to apply himself to it.

They have declined to do a couple of Dean and Cas scenes as originally written, most notably Cas getting his coat back in season 7, on the basis that the dialogue was ludicrous and wildly OOC, particularly for Dean. The version as transmitted is simply done without any dialogue at all. (Some of the conversations between Dean and Sam have apparently been altered for the same reason -- consistently in the direction of Dean expressing himself non-verbally instead of out loud.) Collins apparently remarked that it was the "gayest thing we've ever filmed," and given that he readily cops to saying exactly that, it seems to have been an observation rather than snark. Reports vary on whether Dean was originally scripted to outright say "I love you" at the end of the fight in 8x17, and if so, who changed the line. (It still appears in the gag reel for season 8; the context suggests that Ackles was having trouble getting it to sound right, and that they eventually decided to scrap it as not working after wrecking several takes.) Reports do not vary on the fact that the script only specifies that Castiel heals Dean at the end, and that the palm to Dean's face and clutching at Cas' arm were entirely down to the actors.

My personal read on the actors involved -- and this is based on blind stupid instinct, so you should not in any way put any stock in this -- is that Ackles is probably straight but not especially preoccupied with it. He's taken at least one role before which was explicitly bisexual in the script, and this does not appear to have bothered him in the slightest. He does pretend for a living, you know. (He was also a model before he was an actor, which would be a questionable career choice for a hypothetical straight guy who was afraid that gay might be contagious.) Misha Collins, I genuinely have no idea. His personality confounds most of the attention and reaction cues I'd normally use to figure this out. Most notably, he's so sociologist-y that breaking bits of the social contract that he considers harmless doesn't bring up any anxiety responses, and he seems to have such a deep drive to engage with other people that even with complete randos it spills over into the physical if he doesn't keep a lid on it. Based on a lot of nebulous stuff that no respectable scientist would ever consider evidence of anything, I suspect if you really pinned him down, he'd say 'bisexual', but the answer would be about as much trolly revenge for making him choose a tick box as it would be true. He characterizes himself as an ally of the alphabet soup community, so he probably doesn't consider himself culturally queer, as his wife does, but what relationship that has with his behavior and life experiences, I couldn't say.

Collins is getting rather ticked about the accusations of queerbaiting, to the point where he gave someone a serious answer on the topic, which I think might be a harbinger of the Apocalypse. About :25 in he concludes that "I'm not going to talk about this," is probably the right answer, and then he goes and talks about it for the next four minutes anyway. tl;dr summary: Whether it's sexual is up to interpretation, but you think they love each other because they do. The main reason the relationship is ambiguous isn't that they're not serious about it, but that Cas hasn't really got humaning down yet and doesn't work on the same paradigms. (He's also flat told a bunch of fans at a meet-and-greet that Dean was stomping around Purgatory looking for "the guy I'm in love with". He seems to think he's speaking for the other leads and regular writers, as well as himself. I don't have video of this to evaluate, unfortunately. I don't know about other people, but I find it reasonably easy to draw a line between his serious statements and his smart-mouth ones, even in text; whether that line is in the correct place, only Collins could really say.) Collins is sufficiently pissed that he's stopped caring whether he's getting himself into trouble -- he's just picking his words in an effort to get himself into trouble for the thing he actually thinks this time, rather than a random wisecrack.