Disclaimer: I don't own Supernatural, I just like to play in it's sandbox of mixed mythology.
So this is heretical, I'm sure, but I enjoyed writing it. There's explicit spoilers for up to My Bloody Valentine and this takes place between it and Dark Side of the Moon.
This can be taken as slash, but it doesn't have to be; love comes in many forms.
Please review, but no spoilers for anything past 6x12 (I have a good bit of catching up to do).
The amulet always seems to try to pull him to Dean. He understands its connection to its owner, but ignores it, trying to get it to focus on God as it should.
It takes him too long and a meeting with Cupid to put two and two together.
Dean is the (partial) son of God.
John and Mary Winchester had, according to cupid been a… rough pair to match up. They'd fallen in love near the end, supposedly, but their personalities had kept shoving them apart. And fighting couples don't have sex if they don't make it to the make-up sex part of the evening. And, without sex, there can be no children. The cupids had kept on the couple's cases, but obviously something more had been required.
God possessing a human isn't completely out of the question. It takes a special soul to do it, but John Winchester could hold Michael and hadn't broken in the 100 years he'd spent in Hell. The possession wouldn't have had to be for very long either. If God had made sure that the Winchesters would be happy for a little while, long enough to make sure both Dean and Sam would be born… well it made Castiel wonder about the apocalypse.
Dean has visited Heaven and Hell, and risen from Death again and again. Even with help, his ability to keep living is a tad ridiculous.
He is the true Righteous Man. The one who can stop the apocalypse. Nowhere does it specifically say how, nowhere does it say Michael is the answer. Nowhere does it say the true answer isn't a self-sacrificing big brother who has a soul of pure shining white, acting under his own free will.
Plus, Dean gets what he wants. Not the little things, like every girl in the bar and a cheeseburger for every meal. Not even the big things, like a family and stability. But the huge things, like Castiel's own revival and Sam and Dean being on that plane, Bobby surviving the stab wound even if he could no longer use his legs? Those things which matter the most to Dean seem to come through in the end.
Dean Winchester is self-sacrificing and loyal to his family beyond all rhyme or reason. It is loyalty which begets loyalty and love which begets love. Castiel can't help but think of Dante when he considers Dean and tries to understand the root of the man's often illogical actions: "Thus you may understand that love alone is the true seed of every merit in you, and of all acts for which you must atone."
It is love which drove Dean to hell, which was the impetus for Castiel to save him. It is love –too much love- which drove Castiel to break with his brothers and sisters to protect humanity.
Like God, Dean is Love.
And, like with God, Castiel will follow Dean to the universe's end (and the amulet will always help him find his way).