A/N: before you bust me up about timelines, this is a two-chapter ficlet about what could have happened during Goodbye Stranger. Stick 'round for chapter two, it's better (personally).
They look like the same man, but they are not.
Castiel finds this out with his blade pressed to one of their necks, those summer green eyes pleading, Cas, buddy..., and Naomi behind Cas's back like a puppeteer, yelling for him to do it.
They look like the same man, but they are not. Cas tells himself this every time he kills one of them, every time that face, more familiar than his own, lies lifelessly under his hands.
The second to last, number ten thousand and seventy-two, has nothing but infinite sadness in the curve of his shoulders, the edges of his smile almost sweet. He has no words for Cas to hear, not the ones that he so desperately wants the man to say. And he never will.
Cas almost weeps when his blade stabs into the copy's heart, but it is not that man he is killing.
Castiel's face stays solid and unmovable, as if he were carved of granite.
Another copy appears in front of him, and Cas sighs as that man raises a gun to him, hands shaking. It reminds him of a certain warehouse in Sioux Falls.
"No, Cas, no," the copy pleads, raising a hand to Cas as the angel moves forward.
He breaks the wrist with a satisfying crunch, and the gun clatters to the floor. He is not Dean.
"No, Cas, don't," Dean–that isn't Dean–gasps in fear, "Please."
He is not Dean. Cas drives the blade into the copy's chest and draws it out slowly. If he saw this blade without context...
He hears the soft click of Naomi's heels against the linoleum floor. "No hesitation. Quick. Brutal," she says, pleased with her good work. She looks at him and smiles. "Everything's back in order. Finally."
All Cas can hear is the ringing of Dean's last plea in his ears.
The words he so desperately needs to hear fall from those lips he's stilled ten thousand times, "We're family. We need you. I need you," and the spell is broken.
"You have to choose, us or them," Naomi says, and he chooses.
Them.
The blade falls from his fingers and hits the ground with a clear ring, and he fills his empty hands with the angel tablet.
And it fills him with light.
The next thing Cas properly sees is Dean's battered face. Did his hands do that?
It is impractical to smite himself for that.
Cas gently reaches down and touches Dean's face despite the man's protests—so he did injure Dean—and heals his wounds with a flicker of grace. Like candlelight given a stack of dry tinder the rest of his grace hums and grows, tickling the insides of his vessel. His wings shift, eager to spread and let their shadows show.
"I'm so sorry, Dean," he apologizes. Not to just the real flesh-and-blood Dean in front of him, but to all the ones lying in the road to where he is now.
Cas wonders how he thought those copies were real at all. One hand still pressed to Dean's newly healed skin, Cas knows he'll never make that mistake again.