The meat of last night's Supernatural was a "buddy-comedy" adventure in which Crowley, the King of Hell, replaces Sam as Dean's partner in crime. The result is awesomeness, the likes of which this show hasn't served up in ages. Spoilers ahead...
What's great about "First Born" is not just the whip-cracking repartee between Dean and Crowley. Or Mark Sheppard's impeccable comic timing, and his ability to sell an entire scene with afew well-chosen facial expressions.
Rather, it's the fact that the episode actually manages to pull a pretty neat trick: For most of its running length, we believe we're seeing a brand new side of Crowley. He actually seems terrified and freaked out when he finds out that their quest to find the First Blade (the one weapon that can destroy the Hell Knight Abaddon) has brought them to the home of Cain, the First Murderer and most famous fratricide of all time.
Sheppard does a great job of making Crowley appear genuinely terrified to meet one of the nastiest customers in the Bible, which ratchets up the episode's tension as you start to wonder if Dean has finally wandered way out of his depth.
And then, in the episode's final moments (see above), we get a very different version of the traditional "Let's process our feelings by the Impala" scene. And it turns out that actually, Crowley has been playing Dean all along. Crowley pretended to be surprised about the whole "Cain" business, when in fact he was maneuvering Dean into taking on the Mark of Cain and becoming the new owner of the First Blade, so he can have Dean do his dirty work (yet again.)
The fact that Dean is pissed, but also sort of accepts this — even including the death of their dad's old partner Tara, who sets a new record for "soonest death of a badass female in Supernatural" — is kind of amazing. Dean makes a sort of token shrug at threatening to kill Crowley, but his heart really isn't in it.
And it sucks, because Tara was awesome. And she was right that Dean is a moron.
The Cain storyline was also surprisingly great, because this show managed to find a brand new corner of Biblical mythos that it hadn't yet capitalized on, and a decent spin to go with it. Turns out Cain actually killed Abel to protect him from Lucifer, giving himself to Hell in his brother's place — in a very Winchester-like act. And all this time, Cain has been taking the rap unfairly.
Also, Cain trained the Knights Who Say Ni of Hell, and killed all of them except Abaddon. He tried to retire from being a Hell Knight, and fell in love and got married — but then the Knights found him and Abaddon possessed his wife. (It's only thanks to his wife's dying wish that he didn't kill Abaddon.)
It's nice to see the show coming up with a new spin on its old themes of family and redemption and destiny and women getting killed to motivate the dudes.
Meanwhile, in the "B" plot, almost nothing happens. Castiel and Sam kind of hang out. Cas feels sad that he can't taste sandwiches any more, now that he's human again.
Oh, and Cas tries to extract the remaining bits of Gadreel's grace from Sam, so they can use the remnants to track Gadreel and gank the bastard. But he can't do it without possibly killing Sam, so he stops short — thus proving that Cas has changed, and he's no longer as much of a bastard as he once was. Oh, and Sam wants to kill Gadreel because it'll make up for all his mistakes, such as not closing the gates of Hell when he had the chance.
Sam doesn't even realize that Tara, the coolest new character we've met in ages, died in this very episode because of Sam's decision not to close the gates of Hell. Not that we're bitter or anything.