Castiel had been around since Earth's genesis. Since the beginning of the human race, he had quietly sat in heaven, keeping a steady eye on the people who he observed so skeptically. They intrigued Cas, with every little thought and feeling that that existed within their minds. He studied the emotions, both good and bad; happiness, sadness, anger, jealousy, greed, and lust. But the one that interested him more than any other, was love. For thousands of years he watched as humans lived, died, and killed for love. He examined this emotion from merely a third-person perspective, never experiencing it for himself. Then one day, he received an order to retrieve one of these human beings from Hell. His name was Dean Winchester.
In the short time Castiel had known Dean and his brother Sam, they had been responsible for starting the apocalypse and ending it. Not long before, Castiel had seen the human beings as powerless little ants, simultaneously making love and war, but he admired the brothers. Their commitment to saving lives and protecting each other was something beautiful.
He quickly grew to care for them, especially Dean. Castiel had saved Dean from Hell, pulling him out, leaving his handprint scorched into his shoulder. He felt connected to him, a profound bond, drawing him to the human. These feelings he held for Dean in his heart were new to him entirely. He wasn't quite sure how to define them, and he wasn't sure how to deal with them, but he was sure that he was responsible for him.
It was six months ago that the Winchesters had saved the world from Lucifer. Sam had decided to sacrifice himself, giving Lucifer permission to enter his body, only to retake control of his mind and jump back in the cage. Both Castiel and Bobby had died during this encounter, and Dean beaten to a bloody pulp. The last thing Cas remembered before exploding into a cloud of red at the hands of Lucifer, was protecting Dean from Michael. Something had brought him back, but he wasn't sure what.
When he returned, he saw the lump on the ground, taking slow heavy breaths, covered in his own blood. He kneeled down beside Dean and pressed two fingers to his forehead, watching the life reenter his green eyes. As Dean gained his strength back, his eyes, locked on Cas, transitioned from a sleepy emptiness to somewhere between confusion and relief.
"I saw you - die.." Dean said, his words broken between raspy breaths. Castiel said nothing, and walked towards Bobby's lifeless corpse. He mirrored the act of healing Dean, resurrecting Bobby, and looked back towards Dean. The hunter was no longer looking at Cas but at the spot of grass where his brother had sunk into Hell. The angel's eyes narrowed with concern as he watched droplets well up in the eyes of his human. Dean had just lost the person who meant most to him, who he had practically raised, and Castiel couldn't do a thing about it.
Dean stood, his knees buckling under his grief. He brushed himself off, and looked down, almost as if he was hoping Sam would dig himself up. Castiel saw the expression in Dean's eyes change, remembering the promise he had made to Lisa before the battle occurred. The angel knew he wouldn't be speaking with his hunter for quite some time. He hesitated to flutter away, having the urge to remain with Dean, to rid the pain from his eyes. But Castiel knew in his newly functioning heart that he had to let Dean go, at least for a while. And he was gone.
Castiel needed a break from all the violence and pain he had encountered over the past couple of years. He spent his time visiting some of Earth's beauties that he had grown so fond of. He would sit quietly in the sunshine, with his eyes closed, listening to the trees blowing in the wind, and allowing the warm sun to beat down on his skin. But he came to realize a certain emptiness that existed within him. He had lost his motivation, his reason to feel. He had lost his friends. One of them was trapped in Hell, while the other had begun a new life, with apple pie and a white picket fence. Castiel thought about Dean often. He hoped that his hunter was happy, but he couldn't avoid the urge to stay near, making sure he was safe.
One day the longing become too much for Cas, and he teleported over to Dean and Lisa's house, remaining invisible to his hunter. He leaned against an old oak tree as he watched Dean mow the lawn. He studied his friend, glistening in the rays of sun on the hot summer's afternoon, squinting his eyes under the piercing beams. Cas felt the corner of his lips curl up in a smile as he saw Dean for the first time in what seemed like a ages.
Dean whirled around toward a sound coming from the house. Cas looked to see a woman, so beautiful, with olive skin, and shiny dark hair, walking toward Dean with a icy glass of lemonade in hand. He grabbed Lisa by her waist, revealed under the hem of a tight pink tank top and brought her into a loving kiss.
"Thought you might be getting thirsty out here," Lisa said, her voice pouring out of her lips like honey. "Don't want you getting heat stroke, now do we?"
Dean smiled, pulling her in for a second peck on the lips. "I'm the luckiest guy on Earth," Dean responded, admiring every inch of her lovely face.
Castiel's smile shriveled as he felt a pain in the center of his gut. Now this feeling was certainly unfamiliar. While he had grown accustomed to happiness, fear, sadness, and anger, this emotion was something new entirely.
After being separated from Dean Winchester for quite some time, Castiel felt obligated to watch over him, to protect him - and his new family. He remained in the shadows, never revealing himself to his human, never reaching out to him, no matter how much he desired to. He watched as Dean lived the life he had always deserved. He ate dinner at a dining room table, sat on the couch with his arm wrapped firmly around Lisa, stroking her hands with his calloused fingers, and slept in a bed much more forgiving than those found in cheap motels. The angel knew his friend was happy.
After a week, Castiel sat in the arm chair in the corner of Dean and Lisa's bedroom, watching them sleep. Castiel found an immense amount of comfort in Dean's peaceful expression as he dreamed. The angel looked down, thinking he maybe should leave the hunter alone, allow him to live in this fantasy world. As he readied to flutter away, he heard a stirring come from the bed. Dean flinched, his forehead screwing up in frustration, his square jaw clenching, still remaining asleep. He flinched again, this time making a pained groan.
"Sam…. no.. no.. leave my brother… alone.." Dean spoke restlessly in his sleep, concerning Castiel. The angel watched the hurt flourish on Dean's face. His eyes squeezed closed and his arms moved in a feeble attempt to save his brother from whatever threat he was facing in the dream. Cas knew Dean was only suffering from a nightmare, but he needed to fix him. The angel sat on the edge of the bed where both Dean and Lisa lay, unaware of his presence. Castiel looked down to where the hunter's hands lay tangled in the sheets, his knuckles turning white from the strain as he tightened his grip. He softly rested one hand on top of the hunters, stroking the scars that freckled his leathery skin. His second hand reached over to Dean's tensed shoulder. Even in the dark he could make out the pink handprint that still remained. His thumb began rubbing gentle circles into his muscle.
"Dean… it's okay, you're safe. I'm watching over you." whispered Castiel, his thumb keeping a steady rhythm as he tried to sooth the human out of his nightmare. He moved his hand from his shoulder, to the hunter's jaw, continuing the caresses. "I won't leave you," Cas said, barely out loud. Dean's muscles softened, his shoulders and hands relaxed. Another sound came from the hunter's mouth, but this time, it was not his brother's name.
"C-Cas…" Dean mumbled. Castiel's eyes filled with worry, as he feared he had awoken the sleeping human. But he did not open his eyes. "Cas…" Dean said once more, his heavy breaths slowing, and the sides of his mouth pulling a slight smile. Castiel sat like that with his hunter, keeping a steady eye on him, as he drifted into a calm sleep.