Sometimes he looks at Dean and has to remind himself to breathe.
He’s an angel, or maybe something somewhere in between now; he has no need for respiration, but it doesn’t matter. Humans have always been beautiful to him, with their entire histories and skeletons and molecule arrangements laid out like star maps at any given moment. It was overwhelming, at first, when he touched down on earth with his garrison. Every human that met his eyes just burst with information and color, and he had learned to tune it out. Constellations were just a part of the sky, after all.
But Dean? Dean is an entire universe. The entire spectrum of color bursts out from him, dotted with light and swirling pools of dark and heights and depths and everything that spans the two. Rivers of white energy surge between each nexus, and void-like black seeps in at the edges. He sees Dean’s complexity: the waves of purple he gives off when he’s hiding something, and the red tinted haze that permeates the air when he fights. And when Dean smiles, his aura turns yellow-golden, brighter than any sun Castiel has ever seen. When he leans back on his bed, headset on, feet twitching to the beat, the pale blue puffs of nebulae float off his skin. And then Cas sees the green pillow sailing past his face as Dean halfheartedly throws it to get Cas out of his room. Pink seeps under the door when he’s embarrassed. And Cas has never seen such vibrant color.
He’s never really been able to put his finger on what love is. Humans always made it so messy, with their deathbed declarations and manipulative manifestations. Maybe because love is all he was created in, or maybe, since he descended into Hell, he’s never gone a moment without feeling it. The moment his energy touched Dean Winchester, he was lost. He could see the infinite expanse of Dean’s soul unfurling inside his head, and struggled to contain it. Every color ever visible to any creature with the ability to perceive it exploded in his would-be retinas. It was by God’s will alone that he made it out, dragged Dean topside, and retreated to gather the shattered pieces of himself.
It would be years before he could understand that strange new feeling, that mauve ache that had taken up residence in the space where a human heart would be. But he saw it in eyes of green, and between brothers covered in brown and red grime, and in the maroon devotion of hunters who would and did die for each other. He saw it in pink births, and grey deaths, and white weddings, and orange festivals that lasted from sunrise till sunset. Castiel saw how the blue ocean kissed the tan shore, meeting it over and over, and felt such peculiar purple longing drop into his chest. Longing that burned into him, till it was eased in those green eyes.
So when he has the phantom feeling in his vessel’s lungs to draw in air, to inhale life, to take in curls of color, he pauses. Regards Dean’s vibrance.