Eightball - Dean/Castiel and Supernatural Season 8 Predictions
SPOILER ALERT: POST CONTAINS DETAILS THROUGH 08X19 "TAXI DRIVER"
Dean/Castiel aka Destial becoming canon
I'm not sure it'll be that simple.
Dean has complex/deep feelings for Castiel
It's very clear that Dean's feelings for Castiel are incredibly strong and complex. He mourned the angel's death for over half of Season Seven in spite of him hurting Sam and causing so much pain (consider Ellen's message from beyond in 07x07 "The Mentalists" - "If you don't tell someone how bad it really is...[she'll] kick his ass from the beyond. You’ll have to trust someone again eventually.") Then in 07x17 "The Born Again Identity," Dean leaves Cas with Meg because "If word gets out, we can't protect him. Not really."
The only person Dean's ever really let off the hook is Castiel.
Dean / Meg
Dean put up with Meg because of Mutually Assured Destruction/Taking Down someone with more power (06x10 "Caged Heat"; 07x17 "The Born Again Identity"; 07x21 "Reading is Fundamental"; 07x23 "Survival of the Fittest"; 08x17 "Goodbye Stranger) even though he hates her for killing Ellen and Jo, possessing Sam, etc.
Dean / Crowley
Dean's made tentative allegiances with Crowley (05x10 "Abandon All Hope"; 05x20 "The Devil You Know"; 05x21 "Two Minutes to Midnight"; 07x01 "Meet the New Boss"; 07x08 "Season Seven, Time for a Wedding"; 07x22 "There Will Be Blood"; 07x23 "Survival of the Fittest") but had no beef trying to gank him when Crowley was the mastermind (06x08 "All Dogs Go to Heaven"; 06x10 "Caged Heat"; 06x19 "Mommy Dearest"; 06x20 "The Man Who Would Be King"; 06x21 "Let it Bleed"; 06x22 "The Man Who Knew Too Much"; Pretty much all of Season Eight).
But the Meg/Crowley situations were like the one with the Alpha Vampire; it's not that they're friends, just unwilling allies.
In 06x16 "And then there were none", Dean gives a "pass" for everyone, all the crap they've ever done, over Rufus's grave. But let's face it, he didn't let Samuel off the hook; he's never let his brother forget his mistakes. Hell, Dean's never forgiven himself for half the crap he's done.
Dean / Sam
Admittedly, Dean lived with Sam's demon-blood-drinking, Ruby-cahooting, raising-Lucifer-from-Hell crap, but can you really say he forgave his brother?
Season 4
Dean spends most of the season yelling at his brother for his "psychic crap" and has a falling out with him right before Season 5.
Season 5
Dean spends most of the season questioning his brother's ability and slowly losing faith in him, almost giving in in 05x18 "Point of No Return."
Season 6
Dean spends the first half of the season questioning Sam's behavior; then spends the second half of the season keeping Sam/his hell-baggage in line.
Season 7
Dean spends the three-quarters or so of the season worried about Sam seeing Lucifer. He's too wrapped up in Bobby's death/haunting and killing Dick Roman to put too much effort into Sam thereafter.
Season 8
Dean was pissed with Sam until 08x07 "A Little Slice of Kevin" (after Castiel shows Dean he pulled away back in purgatory and it wasn't his fault). In 08x08 "Hunteri Heroici," Sam and Dean are fine... but in 08x09 "Citizen Fang," they have another falling out. As soon as they start the trials, Dean immediately becomes worried and starts doubting his brother. Again.
Dean / Dean
To be fair, Dean doesn't let himself off the hook, either.
Season 2
Dean hates himself because his father made a deal to save his life.
Season 3
It takes Dean months to admit he doesn't want to go to hell. He spends most of the season trying to sacrifice his own life to save others. He finds himself unworthy to be alive, especially since his father died for him.
Season 4
Dean hates himself for torturing souls in hell "and liking it." He doesn't believe in himself, not really, and when he finds out that he broke the first seal, and will be the one to "save everyone," he tells the angels they're screwed. They should find someone else. 04x22 "Lucifer Rising" is particularly telling when Cas says, "What is so worth saving? I see nothing but pain here! I see inside you, I see your guilt, your anger, confusion. In paradise, all is forgiven. You'll be at peace. Even with Sam."
Season 5
Dean slowly loses faith in himself, in his brother, and his cause. Even though he doesn't give up when he has a chance, he's pretty damn close. And it's pretty clear he hates the fact that he survived and Sam did not.
Season 6
Dean is conflicted over Lisa/Ben as well as Sam. He desperately tries to be loyal to Cas, and when he finds out he's wrong, Dean doesn't fair so well.
Season 7
07x04 "Defending Your Life" makes it pretty clear that Dean hasn't let go of much of anything. He's grieving a lot of crap, blames himself, and on top of that, Cas is gone now and Sam is a little nuts.
Season 8
08x15 "Man's Best Friend with Benefits" Sam addresses the fact that Dean "can't trust anyone but [himself]." But in 08x14 "Trial and Error" Dean wants to take on the trials because he believes he'll die at the end of them, and he can't detach himself from "the job" of being a hunter. He has no happy ending.
I'd argue that Dean hasn't really forgiven himself for anything. He doesn't see himself as someone worth saving; he didn't in 04x01 "Lazarus Rising" and he still doesn't now. Dean just doesn't let himself off the hook.
Dean / Castiel
That brings me to the Dean/Cas dynamic.
Not only does Dean spent who-knows-how-long scrounging in Purgatory looking for the angel to save him, but then he refuses to leave him. This is the dude who broke Sam's head, tried to kill Sam and Dean, and killed thousands of people (and angels) while pretending to be God. The dude who brought Leviathans into the world, which resulted in Bobby's death and pushed Sam and Dean as far off the grid as possible. Then he got amnesia, then he went off his rocker, as Crowley put it, trying to redeem what he did to Sam. None of that absolves him of the deaths he caused, especially not Bobby's death via Dick Roman. Yet Dean fights tooth and nail to pull him out of purgatory; certainly not something he'd do for Meg, Crowley, or... well, really anyone else but Sam or Bobby.
And Sam is his blood. So we know when Dean tells Cas he's family, he really means it.
Castiel loves Dean
I could score through the series looking for indications that Cas loves Dean, but that'd basically be me listing all the episodes Cas is in, even in the episodes where they are "enemies." But some notable instances:
06x03 "The Third Man"
Cas tells Dean they have a "more profound bound" than Sam and Cas.
06x17 "My Heart Will Go On"
Cas sinks the Titanic and loses 50,000 souls he could've used to win his warn in Heaven to protect Sam/Dean.
07x01 "Meet the New Boss"
Cas doesn't kill Sam/Dean at the beginning of the episode, no later when Dean tells Death to "kill him now." Instead, he unbinds Death and leaves. Then he promises Dean that he will 'redeem himself.'
08x07 "A Little Slice of Kevin"
Cas is sprung from Purgatory. Who is the first person he reaches out to? Dean. Not Sam and Dean, just Dean. Even though he's not at full power, he keeps trying to meet up with Dean. He doesn't even get cleaned up first.
08x10 "Torn and Frayed"
Cas needs help and immediately goes to Dean. It takes him a while to notice Sam is not there. When he is ordered to lie to the Winchesters, he does it very badly, even for Cas.
08x17 "Goodbye Stranger"
Again, Cas lies badly to Sam/Dean. I mean, Cas has lied a LOT better in the past. Then Dean helps Cas break his connection with Naomi's mind control.
Overview
Dean has strong emotions for Castiel; it's definitely love, possibly even sexual attraction. Cas's feeling towards Dean are very clear as well. But is the relationship romantic in nature? Are the feelings romantic in nature? After all, Bobby was family but he wasn't blood; I don't think anyone would try to argue that Bobby/Dean or Bobby/Sam was canon. Of course, the dynamic between Cas/Dean is markedly different than Bobby/Dean, but the point should still be made: the Winchesters do 'adopt' family members who are important to them, close as blood, so to speak.
So while I think it's clear Dean/Cas love one another, there are some hurls to deal with. Neither character has (verbally) owned up to their feelings directly. Neither of them has gives owned up via intimate physical contact, either.
In this way, their relationship is very similar to the Mulder/Scully dynamic, specifically in Seasons 6, 7, and 8. There are indications, implications, and others opening acknowledging their close relationship, but on screen, the obvious/intimate contact is exceptionally limited. It's insinuated that Scully and Mulder had sex; but they never talk about it. Don't even get me started on the fact that Mulder/Scully almost never speak about Mulder being the father of her baby directly. It's implied, the viewers all assumed it, and it's technically "canon", but not like other relationships (i.e. Booth/Brennan on Bones or Castle/Beckett on Castle).
So, will we qualify Dean/Castiel as canon if they have a similar situation? Implications of a physical relationship, but no direct communication about it, no direct sign of intimate contact on screen? I think the show is likely to go in that direction, if any at all.
Summary
Will Castiel/Dean be in a relationship and make Destiel canon as of Season Eight? I'm betting on the "sort of" column; mostly because I'm doubting an overt relationship will crop up. In Season Nine? I'm thinking that will be a better candidate for Destiel to be canon/overt.