THEN! The Winchesters met a demon named Meg. Among her hobbies were killing the their friends, giving Castiel nicknames, and speaking in a weirdly slurry kind of way. Castiel managed to overlook all this and planted a big kiss on her, declaring, "I learned that from the pizza man!" I had to cast back into my memory to figure out when Castiel got kissing lessons from a pizza man, then remembered he was referring to some porn he'd peeped. It eventually behooved Meg to work with the Winchesters, rather than against them, which put her on Crowley's bad side. In this season's plot developments, Castiel got drilled by an angel named Naomi, and not in the pizza man way. She brainwashed him into killing Heaven's Most Adorable Angel in order to keep safe her deep, dark secrets. Or something. Crowley had already learned of the existence of the Angel Tablet by that point, so the only people in the dark were Sam and Dean. But the show couldn't have them knowing about the Angel Tablet while they were still hot and heavy after the Demon Tablet, which God's Grubbiest Prophet was hard at work translating. With GGP's help, Sam and Dean undertook the first of three trials that had to be completed before they should shut the Gates of Hell. Dean was raring to take on the trials himself, but Sam beat him to the punch by killing a hellhound and subjecting himself to what looked like squid ink bukkake. As a result, Sam contracted an STD (satanically-transmitted disease) and started coughing up blood. Dean prayed to Castiel about this, but got no reply from his very own personal angel.
NOW! Dean Winchester skulks around the darkened interior of some random plant or factory. Unlike the random plants and factories we usually see on this show, this one seems rather shiny and clean and new. This is our first hint that something is Very Weird. Where's the rust to which we've become accustomed? The oozing oils of unknown origin? He has his gun at the ready, but his weapon proves useless when an unseen foe knocks him to the ground from behind. Castiel advances on him from the shadows. "No, Cass," Dean pleads, raising one hand in a useless gesture for mercy. Castiel grabs his wrist and snaps the bones. With his other hand, he produces his All-Purpose Angel Sword.