It is regrettable, but necessary. The damage this child could inflict upon the Host of Heaven – upon the entirety of Creation – is too great to risk. You must destroy it.
You attempt to reassure it; though the half-demon must die, there is no reason it should die afraid.
It is afraid, though. Clearly, it does not trust your words of comfort. Its eyes expand with terror as it backs away from you… or perhaps it simply feels you are intruding on its 'personal space', as Dean so often does? Either way, the child is tactically unskilled, backing into a corner in that way. Certainly, the walls afford some small protection against corporeal beings, but they also prevent escape. You admit to yourself that killing a child, so helpless despite the power in his grasp, is an uncomfortable notion.
Nevertheless, it must be done.
"I'm sorry," you tell the child as you advance upon it. You raise the demon-killing knife you borrowed from the Winchesters, preparing to put to an end once and for all the terrible menace hidden within the child… who is suddenly taller than you expected. A great deal taller, in fact. If you stretch to the full height of your vessel, you might just be able to plunge the knife into its shoe. You are not sure if that will effectively destroy it or not; it will most likely harm the child no more than would a pin prick. Still, you must try, which means crossing the great expanse of carpet which has interposed itself between you and your target.
It is at this point that you realize you are unable to move your vessel. You are unable to move at all. In fact, you realize, you cannot even vacate your vessel to do battle with the young monster in another, larger form. You are trapped.
You can, however, expand your consciousness within the confines of your vessel. You do so, and discover that your vessel is no longer a thing of varied composition, of fluids and cells and life. The feet are connected to an unmoving pool of inanimate material – plastic. Indeed, it seems your vessel's feet are made of plastic. You discover that this is true of the whole of your vessel.
At the same time, it occurs to you that the child is not the only thing in the room that is inordinately large. From there, you make the inference that the child and the room and the world are not large after all. Rather, your vessel is very small.
You conclude that the child has turned your vessel into a tiny plastic model. You are imprisoned inside, and there is nothing you can do about it.
This is what you feared. You imagine the entirety of the Heavenly Host, all of your brothers/sisters reduced to an army of impotent playthings as demons sweep across the earth, led by Lucifer.
The door bursts open, and the Righteous Man enters, followed by his brother, who is, of course, Lucifer's vessel. You hear them ask about you, and the boy wordlessly points to you. The world spins and tilts alarmingly as you are seized in seemingly enormous, warm fingers. Dean stares at you as he holds you in his hand, which strikes you as odd considering that he always complains when he notices you observing his soul. You wish to ask him about this, but you cannot speak bound as you are.
Then Dean is placing you on a shelf as he denies any association with you. This does not offend you, of course. There is no sensation of 'hurt feelings', as a human might experience; angels know nothing of such feelings, and you are still an angel, albeit one trapped in a diminutive vessel of plastic.
Your contemplation of your uninjured feelings, or lack thereof, has in no way impaired your awareness of the exchange occurring between the Winchesters and the boy. They are in the process of telling it a string of fantasies in order to persuade it to come with them when you sense the approach of a demon. You struggle within your plastic prison to do something, anything to warn them what is coming, but you are utterly ineffectual. Dismayed, you are forced to watch as the demon overpowers the Winchesters and begins its own campaign to sway the child to its cause. What is truly infuriating is that the words the demon uses to tempt its offspring, though distorted, are half-truths, while the Winchesters had engaged in nothing but falsehood.
It provokes the child to anger. The lights begin to flicker, the fire to flare beneath you – sure signs of a gathering of spiritual power. The building shakes violently, flinging you from the narrow shelf on which you stand so you experience for the first time what it is to truly, physically fall.
It is terrifying.
You're hurtling through space with no control over your path of flight, descending toward the floor with no way to stop yourself or to brace for the dreaded impact. But then, perhaps the impact will never come. Why should a falling angel stop falling? Why should you not continue to sink through the floor, through the earth, through oblivion and straight into the Pit of Destruction?
Yet it does come. The carpeted floor forcefully arrests your descent, nearly jarring you from the plastic vessel. If only it had – then you would be free to assist your humans and rescue them from the clutches of the demon, though you would be forced to do so in your true form. As it is, you are powerless to help, or even remove yourself from the floor, where you will likely be trodden upon. You are not eager for that unfortunate event.
But the Boy with the Demon Blood is speaking. Perhaps it is because of the demonic taint he carries that he is able to reach the angry half-demon. The boy quickly puts away the demon who threatens Sam – you glean a certain amount of satisfaction from that – and listens attentively while Sam pours out the truth. The boy is frightened. It – he worries for his parents, even the mother he has never yet known. He cringes from the responsibility which settles heavily upon his small shoulders.
And he stands. You see the light burst forth within his soul, his mind clear. You see his purpose. He intends to hide himself away, away from everything and everyone, for the safety of those he loves. He will assist no side – not angels, not demons – but will seek only to protect whatever humans he can from the coming storm. He exorcises the demon with a command, doing what you could not and releasing the Winchesters from its power.
As soon as Dean has recovered, he retrieves you from the floor. Gravity is of little import to angels, yet it is somehow nice to be upright again. There is a sensation something like warmth when Dean attempts to negotiate your release.
Jesse looks incredulous. "He tried to kill me," he reminds Dean.
This is fair. You did try to kill him. That, you can see now, would have been a grievous mistake.
Looking nervous – with good reason – Dean places you back on the mantel and suggests addressing the issue of your continued plasticity later. You are unworried; you can see that young Jesse intends to put right all the changes he wrought in reality, just as you can see that, when he asks for a moment to say goodbye to his parents, he is really creating a chance for himself to slip away from the Winchesters and go into hiding, where none can find him.
You begin to wonder how long he will be about it. Angels can stand still indefinitely, but something about knowing that you are actually unable to move makes you crave motion.
The Winchesters go upstairs in search of Jesse, leaving behind a sense of loss. You wish you could tell them that he has already gone.
Then the head of your vessel connects forcefully and painfully with the ceiling of the room. You can't straighten to the body's full height, and you tumble off the suddenly-narrow mantle and land on the floor in an undignified heap. Your wings are sprawled awkwardly beneath you – the left one will likely bruise – and the long coat worn by your vessel has flipped up over your face. You decide you are fortunate that the Winchesters were not present to witness that.
You dust yourself off, heal your bruised wing, and join the Winchesters. As you explain to them that it will be impossible to find Jesse, you are intrigued to discover that you are pleased with this outcome. You are glad you did not succeed in killing him, and that he has escaped both you and the Winchesters. Indeed, he has escaped anything that might potentially try to interfere with him. Why you are pleased at your failure in this area is a mystery you will deal with later; for now, there is a child alive and as safe as anyone can be during the Apocalypse and that? That is enough.