Supernatural season 11 premiere: Five plot predictions for Sam, Dean and Castiel when show returns

The Supernatural season 10 finale left fans on tenterhooks with a mysterious new evil swallowing up the Winchester brothers, and Castiel going after Crowley under the influence of a spell by Rowena.

In a new trailer for season 11, Jeremy Carver teased a dark season ahead, and said, "For the boys [Winchester brothers] things are going to go from bad to worse."

Here are a few plot predictions for season 11:

Darkness will play a huge role

In the Brother's Keeper, Death reveals a terrifying new mythology, which dates back to before earth was created.

Before God created the world, there was a "destructive, amoral force" called the Darkness. God and his archangels managed to beat back and lock away the force, and God created the Mark as a lock and key. The creator bestowed this Mark on Lucifer, who was driven to jealousy of mankind by the Mark, and he shared the Mark with Cain.

As long as the Mark exists, the Darkness is locked away. But when Rowena performed the spell to remove the Mark of Cain, it unleashed the Darkness, which has, thus far, manifested as dark bolts of "electricity" and smoke. These were the bolts that swallowed up the Winchesters and their car when we last saw them.

A major plot for season 11 will be how the Darkness will manifest, and how it will affect the Winchesters directly after swallowing them up. Could they become possessed or hurt from it or was it just a dramatic finale?

Will Archangels or God appear?

Death made it clear that God and his archangels fought together to defeat the Darkness plaguing the universe before creation.

So the question remains: Will God appear in the series? If it took the father of the universe to defeat the Darkness before, will it require the same strength this time around as well?

Unfortunately, the Supernatural universe is running low on God and his archangels right now. God hasn't really been seen since season 5, and the majority of archangels are either dead or trapped in Hell like Lucifer and Michael.

If we assume that the Darkness storyline can last long enough to take us to the series end of Supernatural then this could be an opportune time to bring God, Lucifer and/or Michael back for a final showdown on a celestial scale.

Fallout from Dean killing Death

In a shocking move, Dean killed Death to avoid killing Sam in the Supernatural finale. While Dean did this to save his brother's life, it's obvious he didn't really consider the potential ramifications of killing one of the universe's oldest beings. Death has always been about maintaining the natural order of things on Supernatural, which is precisely why the Winchesters anger him so much: they keep tampering with the natural order.

Now that the horseman of Death is gone, and since Dean killed him with the reaper's Scythe, is Dean the new Grim Reaper?

Will Castiel kill Crowley?

Things were not looking good for Castiel in the Supernatural season 10 finale. Rowena double-crossed both the angel and Crowley, used the "attack dog spell" on the angel, turning him into a feral creature who is hell-bent on killing Crowley.

Fans have seen Rowena use this particular spell before, but in one of the cases it killed the person who was under its control. Will Castiel be able to fight the effects?

We may see a major showdown between the demon head and the angel in the season 11 premiere.

Rowena, as the a new villain

The finale confirmed that Rowena has no love or sympathy for anyone and Crowley has little love for his mother and would be happy to see her gone. Unfortunately, she's now running free and is armed with a great deal of power. Will she become the new ruthless villain for season 11?

The finale's end moments saw her leaving the warehouse after putting a spell on Castiel to kill Crowley for her. Her next step could be trying to take over Hell's throne. Season 11 may find Crowley working with the Winchesters and Castiel to defeat Rowena.