It looks like Dean Winchester has really gone off the deep end.

'Supernatural' season 10 episode two, 'Reichenbach,' took a darker turn from last. Dean isn't singing bad karaoke anymore or getting snarky with his new BFF Crowley.

After abandoning Sam in the hands of a stalker obsessed with revenge, Dean finally embraces his inner demon. Crowley tries to reel him in by feeding the Mark of Cain's bloodlust with targets. In classic King of Hell fashion, he attempts to control Dean's penchant for violence and harvest souls at the same time. Things doesn't go as planned, though.

Dean decides he doesn't want to be Crowley's "bestie" anymore and ditches him. They end their "relationship" with Crowley throwing in classic break up lines to an unfazed Dean.

'As it turns out, Dean doesn't want to be a brother either.

When they finally meet, he tells Sam that he wants to rip his throat out - with his teeth - but the determined little brother that he is, Sam attempts to use the demon cuffs on him. Unfortunately, Cole breaks up their sibling rift and challenges Dean to a fight.

After being banged around a bit, Cole finally gets to cut Dean's face only to see it heal right in front of his eyes.

"What are you?" Cole asks.

"I'm a demon," Dean says, simultaneously flashing his black eyes at his shocked opponent.

Dean doesn't kill Cole, giving viewers a bit of hope that his humanity is still intact. When Sam points that out later, however, he says keeping Cole alive isn't mercy, it's basically torture, not being able to kill the guy that killed his father.

'Supernatural' season 10 and Dean, in particular, seems to be getting darker by the episode.

This just made Castiel's earlier defense of the Winchester boys to Hannah more than a little ironic.

"Sam and Dean may be a bit rough around the edges, but they're the best men I've ever known. And they're my friends," he says. Question is; will Dean ever be good again?

His lost of interest with the Impala, in particular, is a telltale clue to his sinister transformation.

"This thing is filthy," Sam says about the classic car.
"It's just a car, Sam," Dean says.
"It's just a car?" Sam asks in disbelief. "Wow, you really have gone dark."

Now that Sam finally has Dean, will he try to cure him? Will Cole become a full-fledged hunter now that he knows his target is a demon? And did Crowley really think of Dean as his best friend?

Catch 'Supernatural' season 10 every Tuesday on the CW.