He knows of a power in his body. It does not reach his fingerprints.
In middle school Dean is an average student. There isn't time for homework when there's a brother to be looked after, a father to try and keep sober. His teachers remark that he's such a bright boy; it's a shame his work ethic seems so low, but they don't know the half of anything. In the margins of his notes sometimes he writes whispers: I probably saved your life, you old bag. Old man. Old frauds.
In English class against all odds he excels and that is the place where he learns the words for what he is. In books he pauses to linger on the oh of borrowed, the air of aware. In a fluorescent excuse for a science lab his teacher explains the mechanics of the ulna and the radius; it is as if he is explaining Dean. He sinks into his textbooks late at night after Sammy is asleep to trace the skeletal diagrams with his fingers.
“Is that where you are?” he whispers, sometimes aloud, rubbing the silky paper above the cartoon sternum, imagining all things hollow and full of light.
There are hundreds of points on a perfect circle from which a straight line can be drawn in any direction, and that is how Castiel speaks, from a point on the rolling curve of the top of Dean's skull. His voice is a pressure on the butterfly bones of his face. That is where I am.
He can sit for hours on the apartment balcony, holding his arms out, hands palm up. The power follows the path of his touch when he traces the jutting of his wrists, the sharp points of his elbows; it runs like warm sparks under his skin but never leaves it. Blood and muscle and tissue and ligament bind it in.
Once he saw an incubator holding tiny newborn chicks and knew that he had found another metaphor, and he pressed his hand against the warm glass until it began to prickle and burn.
The pain when he jars his ulnar nerve, Dean knows, is Castiel's laughter. When he rubs the back of his neck subconsciously his fingers slot between the swells of vertebrae like hands coming together; he is fascinated by the piano-string rise and fall of his metacarpals when he stretches out his fingers. He could almost believe that a music exists in their movement alone.
On apartment balconies or house porches he plays twenty questions with the power. “Are you music? Are you sunlight?” Once, “Are you me?”
Castiel murmurs as a small and curious ache beneath his browbone, I always were, I was, I be. His grammar is muffled in the folding of Dean's arms. You know exactly what I am.
Dean enters high school with meteorites lodged in his spine and nebulas lining the cracks of long-healed fractures. Castiel is an itch too deep to be scratched. Some nights he lies awake with tired eyes raking his fingernails gently, absently, against the knobs of bone he can find with his touch, the rounded mountains of his knuckles or the buzz of his elbows.
He becomes more borrowed, becomes hyper-aware that his flesh is separate, that he owns his skin and his veins, but he does not own his deepest anatomy. Were he turned inside out he would be something other. The power surges and pulses with the tide of his blood but it isn't his to wield. There are days when he feels that he could burn out streetlamps with the brush of his hand or call down lightning with the bend of his wrists, but he can't. Dean is a Tesla coil of sinew and tissue and Castiel is electricity slipping white-hot through his marrow.
“Why are you here?” He fits his fingers into v-shapes against the curve of his eye sockets. “Why my bones?”
I am your bones. They are not yours. They are me. I am.
“Are you ever gonna leave?”
Do you want me to leave, Dean Winchester? Would you rather I were gone and you were spineless and fragile and broken?
—take shelter in someone else?
In the next bed Sam turns over on his side and Dean falls into a whisper, running fingers up the curves of his cheekbones in the dark. Castiel rises to his touch like a cat purring.
Dean is drunk and twenty-nine years old when he tells Sam about the way there's a supernova pounding at his skull. He gives no names. A part of him hopes that his brother will send the mad notion off like a paper airplane and take away the bottle, but there is an arthritis in his hands that says otherwise; his bones have always known best.
Sam listens. He asks only one question: “How long?”
Dean says, “Always.” He pinches the bridge of his nose. In his teeth Castiel echoes it back: always. Always. Always am always were always will always. Tell him my name.
In two months Dean will be dead.
There is a dream that his skeleton leaves his body in the night to court a man with blue eyes, and an ache in every part of him when he wakes from it. The last of the power sparks against his palms like the dying gasp of a firework and then it is gone.
Lilith comes. Her hounds snap his bones in their black jaws. With every break the memory fades, and in Hell there is no butterfly-pressure and no wrist-murmur to tell him that his body was not always empty and he was not always one simple creature, but two; the corpse that is buried is entirely his own. Nothing is hollow. There is no light.
He will remember nothing of meteorites and marrow when he wakes.
Jimmy tells them that bearing an angel is like being chained to a comet. For an instant at most Dean finds himself thinking, that's wrong—bearing an angel is like being, and nothing more. But the thought is gone before he can grasp it.
Dean kisses Castiel on the night after the world ends. For an instant, he feels whole.
Dean is drunk and thirty-three years old when he asks Castiel, “What are you?”
Castiel watches the music of his wrists. “We,” he says.
There is nothing else.