Maybe I'm just really slow to realize this ... but ... if Chuck was the one writing this story the whole time, if he chose our Sam and Dean to be his main characters and then created every foe they fought, every battle they won, if he orchestrated the whole damn thing from start to finish, then that means, every time he resurrected Castiel, it was for a purpose.
Maybe it wasn't always part of his original outline-- because, Cas was the wildcard, the cracked chassis; but any time Chuck tortured the feistier half of his dynamic duo just a little too much, Dean risked no longer cooperating. And whenever Dean didn't cooperate, the story would suffer. A depressed Dean, a defeated Dean, a Dean that had a death wish ... that's not the character Chuck was writing. He needed Dean to always straddle the border between tragedy and comedy, but whenever he took away that man's angel, Dean would dive headfirst into that toxic, tragic-pool and drown himself. So, when Chuck would see the last air-bubbles popping to the surface, he seemed to say: Guess it's time to bring back the angel.
Chuck banked on Dean's love for Cas to KEEP him in line with that hero-character he had envisioned for his story. He knew that no one else could push Dean the way Castiel did, no one else could make the man hope and laugh and be himself the way Castiel could; so every time the angel died and Dean wasn't fun to play with anymore-- BAM -- divine resurrection.
The one thing Chuck could never count on though-- never predict, never control, was just how much Castiel loved Dean back; which is why he killed the angel off time and time again. Chuck didn't like the fact that he needed Castiel. He didn't like resting his main character's continuity on the shoulders of someone who could steal his whole story and run away with it ... but he had no other choice.
He wrote himself into a corner by accidentally making this whole thing a love story; though he thought he could manage it ... just as long as Castiel never told Dean how he really felt...
Because if Dean knew that he could truly be loved just for being himself-- if he knew that all his flaws could not only be accepted, but also be adored, cherished, seen as worthwhile, then he too would no longer be predictable.
Chuck wouldn't be able to keep Dean beneath his pen.
All this just goes to show that the love was reciprocated the whole time-- if it wasn't, Castiel wouldn't have had the power he did. He wouldn't have been able to rip the pages free from Chuck's greedy fingers.
Castiel loved Dean-- that is true; but it was Dean's love for Castiel that made the whole story move forward.
Castiel may have been the cracked chassis, but Dean's love was the coal that powered them all down the line.
