Leviathan!Castiel

Name	Leviathan!Castiel
Actor	Misha Collins
Dates	2011 (vessel could not handle holding the Leviathans)
Location
Occupation	Vessel for Leviathans
Episode(s)	7.01 Meet the New Boss 7.02 Hello, Cruel World

Too late! Cas is umm... He's gone! He's dead! We run the show now. – Leviathan!Castiel, 7.01 Meet the New Boss

Leviathan!Castiel refers to the conglomerate of Leviathans occupying Castiel's vessel, Jimmy Novak during and after his time as Godstiel.

Epsiodes

7.01 Meet the New Boss

"Oh, this is going to be so much fun. (Laughs maniacally)"

Castiel opens a door to Purgatory and absorbs all the souls residing there. He then uses this power to obliterate archangel Raphael and declares himself a new and "better God." Castiel proceeds to perform many miracles and selfless deeds in his efforts to bring peace and order back to the world. Eventually, the Leviathans begin to stir within Castiel and demand to be let out. Castiel refuses to acknowledge them, however, and continues his campaign of righteousness. The Leviathans take their toll by eroding Castiel's vessel, causing him to black out and gaining control of his vessel for a brief moment.

When Castiel comes to his senses, he realizes the carnage the Leviathans have wrought and seeks out Sam and Dean's help in returning the souls to Purgatory. This is only partially successful, however, as the Leviathans succeed in "holding on" inside Castiel and soon after take full control of his vessel, declaring him dead and gleefully attacking Dean and Bobby.

7.02 Hello, Cruel World

"We'll be back for you."

Before the Leviathans can finish Dean and Bobby, Castiel's vessel begins to rapidly deteriorate and oozes black blood. Knowing it cannot contain them all for long, the Leviathans abandon Dean and Bobby with the promise to return and directs the vessel to a nearby water supply. They then submerge the vessel and it implodes, releasing countless Leviathans. Castiel and his vessel are gone, leaving only his tattered trench coat behind, which Dean retrieves.

7.06 Slash Fiction

The Leviathan Chet reveals that as a result of all the Leviathans possessing Castiel, they have absorbed all of his collective knowledge, giving them an advantage in tracking the Winchesters through their aliases.

7.23 Survival of the Fittest

Meg and Crowley reveal that as a result of all the Leviathans possessing him, the resurrected Castiel possesses the ability to tell the them apart no matter what form they take. This proves to be the key to killing the Leviathan leader Dick Roman and putting a stop to the Leviathans' plans. Before dying, Dick thanked Castiel for "the ride into paradise."

Trivia

One confusing argument, is how an angel can become a god. Chuck, God, is still alive, so how did Castiel become "The New God?" Even if Castiel did, in fact, become God while Chuck was still alive, how did he lose to the Levianthans? Wouldn't the angel who is on the same level as God be in control of the Levianthans? If God was the one who made them and locked them away, and Castiel did in fact become something else since he was stabbed with an angel blade by Sam in the Season 6 Finale and does not even bleed, then what did he become? He clearly became more powerful than angels since he is not even phased by an angel blade and able to kill all the angels who followed Raphael. Death mentioned that Castiel looked more like a "mutated angel" to him rather than a god. The only explanation was that Castiel declared himself to be the new God, but in actuality was transformed into "a mutated angel" as Death declared. Hence, the inability to be affected by an angel blade or to completely control the Leviathans when his power was heightened by the souls in Purgatory.