'Supernatural' preview: Could Castiel and Crowley kill Sam and Dean?

spn-king-vid.jpgFriday's " Supernatural" episode saw the Mother of All meet her demise, and dropped a shocking bomb on us: Castiel ( Misha Collins) and Crowley ( Mark Sheppard) are working together. This was especially surprising given the part where we all thought we'd watched Castiel roast Crowley without blinking an eye.

In this week's May 6 episode, we'll finally see some explanation for Castiel's desperate actions throughout the season. He's spent a lot of the season battling his angel brethren for control of Heaven, and that battle is about to come crashing back to earth.

Executive producer Bob Singer tells Zap2it, "We always thought that a war in heaven is best told off screen, but you're going to see a lot of Castiel dealing with his problems coming up. The last run of episodes is very Castiel-heavy. There's some very interesting stuff that we're doing with him. His problem in Heaven will certainly be impacted by Sam and Dean."

In the first clip of the upcoming episode "The Man Who Would Be King," Castiel and Crowley's quest to obtain the souls in Purgatory has reached a climax after Eve's death. There's just one thing standing in our favorite Demon's way.

Okay, two things: Sam and Dean.

"Please. I'm begging you, Castiel. Just kill the Winchesters," Crowley asks, and when begging doesn't work, he threatens to do the deed himself - and to put their souls where Castiel won't be able to retrieve them. After the Winchesters' six seasons of mostly successful monster slaughter, Crowley doesn't like the idea of having them on his tail, though Castiel tells him not to worry about them.

"What, like Lucifer didn't worry?" Crowley rants. "Or Michael, or Lilith, or Alistair, or Azazel didn't worry?"

The man makes a point.

Tune in Friday at 9 p.m. EST. Things are getting good.

Photo/Video credit: The CW