Notes: AU after season three. I'll probably write more in this series. Tell me what you think!

Castiel has been given a mission.

The instructions are straightforward enough: he is to locate the new Boy King of Hell, and destroy it.

It is made slightly more complicated by the fact that the Boy King is currently (constantly, in fact) in the company of the Michael Sword, who of course must not be harmed. That is why the task has been given to Castiel, and not, for instance, Uriel, who is master of destruction but who paints in broad strokes.

Ideally, Lucifer's true vessel would be preserved until the day it fulfilled its role according to God's Plan, but the situation is far from ideal. The Boy King is a half-breed, Uriel tells him. It is an abomination, human by birth and demon by blood, so impossibly arrogant that it dared free its brother, the Michael Sword, from Perdition before the appointed time.

Castiel does not fully comprehend the reasoning on that last point, but he does not question it. These judgments have been made by those much wiser than he, and in any case, the Boy King of Hell is damned by its title alone.

Castiel is obedient.

He sets out.

Castiel miscalculates slightly. He is not accustomed to descending to Earth. He lands outside of the low building which houses the Boy King and the Michael Sword, rather than inside as he had intended. The surge of wasted power causes the lights to spark and sputter, surely alerting the pair of his arrival.

That is . . . unfortunate. Castiel does not take pleasure in battle as some of his brethren do, and he had hoped that his mission might be carried out without even waking the abomination or his brother. It seems that will not be possible.

It is not of import. The Boy King is still undeveloped in his powers and the Michael Sword, while remarkable, is only human. They will not be able to stop him.

He has yet to fully reign in his power, and the door creaks and flies open as he approaches. He is immediately met by a gun-blast, but that is not what makes him falter.

Sam Winchester is staring at him.

The Boy King is not a monstrous hybrid, spewing hubris and malice. The Boy King is just that – a boy. Castiel can feel its – no, his – cracked mind struggling to cling to sanity, and even without his heavenly senses he can see the pain and fear shining in his eyes, bright hazel not entirely obscured by the inky blackness which ebbs and flows around the edges.

Dean Winchester has taken advantage of his momentary distraction to plunge a knife into his vessel's chest.

Here is another curiosity, Castiel discovers as he shifts his attention. This man (or is he a boy, as well?) burns just as the Michael Sword should, but he holds none of the calm faith which Michael does. He is a tumultuous storm of fear and fury and guilt, pitching and heaving like the sea. There is conviction there, yes, and love, but not for Father. It is all directed at the broken boy huddled against the wall behind him.

Castiel had viewed this mission as an honor, but now he begins to think that it may not be so.

Still.

Castiel is obedient.

He moves forward.

"You stay away from him, you son of a bitch!"

The Michael Sword – Dean – has discarded his weaponry and resorted to attacking with his bare hands. Castiel is surprised and, he must acknowledge, somewhat impressed by his persistence, but it is becoming bothersome. Careful not to cause injury, he catches a blow before it lands and uses the moment of shock to send the human into a peaceful sleep. Dean crumples to the ground, and Castiel turns back to the true object of his mission.

Sam Winchester, the Boy King of Hell, Lucifer's vessel. His eyes are on his brother, and he looks afraid.

For reasons Castiel does not entirely understand, he finds himself speaking.

"He is not dead. You are the only one I have been sent to destroy."

Sam looks up at him, eyes clear and lucid.

"I know."

Here is the faith Castiel was looking for. Sam Winchester knows what he is. He believes in his Father. He accepts His judgment.

He is bleeding.

Too late, Castiel sees the sigil painted on the wall. There is nothing he can do as the boy slams his shaking hand into the middle of it, and an instant later, he is in Heaven with Uriel standing over him.

"This is very unsettling," Uriel states as Castiel pushes himself upright.

"Yes," Castiel agrees, relieved that someone else shares his concerns, though he is surprised by the source. "The boy –"

"Should not have known that sigil," Uriel cuts him off. "It seems Lucifer has been reaching through his bars."

That is not what Castiel was intending to say. He was intending to say that the boy is not the thing of pure evil as which he has been portrayed, that he is young and lost and perhaps even redeemable, that he is far more important to the Michael Sword than any of them anticipated, that he is a boy.

Uriel's tone brooks no argument. Castiel falls silent.

Castiel is obedient.

And yet . . . .

He cannot forget the glimpse of Sam Winchester's face through the white light, hazel eyes shining with tears and lips forming two words which planted something almost like doubt in the back of Castiel's mind.

"I'm sorry."