Once humanity touched him, so too did the seven cardinal sins, the ones he shouldn't ever have had to worry about.
Gluttony growled from the pit of his stomach, made his mouth water whenever they walked into a diner and he caught the scent of food on the air. Dean would joke that Castiel was worse than he was about dinner, and Sam would attest to the fact that the question of food made Dean imperious. "I almost killed the kid over the last slice of pie once," he said with a laugh. Castiel just closed his eyes and took another bite of the burger. He hated how delicious it was on his tongue.
Sloth came to him in the night, wrapping soft arms around his shoulders like a blanket. Exactly like a blanket; he learned what a deep slumber was like, and Sloth made him never want to leave. He understood why so many humans slept their lives away. It was a warm, comfortable feeling he hated to stop. It was not unlike Revelation, when the glow of Heaven's light graced his skin. But sleep seemed to last forever. He could even dream. That was something the angels never talked about back in Heaven. Perhaps because their leaders knew how tempting dreams are.
He also thought he understood why the Winchesters slept so little. The soft comfort of sleep was too much at odds with the rest of their lives; it must make them uneasy. And as for the dreams, well. Castiel knew from his nights of watching over them that many of theirs were unpleasant. He thought that was why they made sure they didn't often get the chance to fall into a deep enough sleep for real dreams. It kept the nightmares away more often than the alcohol did.
Wrath took his arms in an iron grip, curled his hands into fists and gritted his teeth. It made him want revenge whenever one of the Winchesters got hurt. He'd felt the need for righteous retribution before. He'd even carried it out a few times over the centuries. But this, this was something else entirely. This was a desire he felt burning in his chest, a low but persistent fire, a passionate and angry need. He'd shake with the effort of holding himself back, knowing that he wouldn't do nearly as well in a fight without his angel's strength.
Envy took a tight hold on his heart, but it did so on behalf of the Winchesters. He saw the people they saved when they went to gather clues; he saw what happy families looked like and knew that Dean and Sam had never even come close. It made him wish they could have it. It made him wish he could be a part of it. Jealousy brought his eyebrows together in a perpetual frown when he saw what they could not have. He breathed a sigh of relief every time they left one such family behind in favor of the road, glad to have Envy loosen its grasp.
Greed possessed his hands so that they grabbed tight, bringing him to latch onto what was his. Soon after Castiel became human, Sam suggested he join the world as a civilian. It was more than either he or Dean would ever get, and Sam thought he might be happy that way.
When he made the suggestion, he found himself pushed up against a wall, Castiel's hands gripping his lapels, a furious look in his eyes. Dean's "What the hell, Cas?" garnered no response for a few long seconds before Castiel dropped his hold. "I chose this life," he said, glaring at each of the brothers in turn. "This life. And I will live it." He'd chosen to join them on the hunt. He'd chosen them, and he had no intention of ever taking that back.
Lust trailed her fingers down his cheek, soft and gentle, the ghost of a touch that left heat in its wake. It left him craving more. It left him breathless when he realized how close he stood to another's body, left his pulse quickening at the brush of a hand against his, left his lips parted of their own accord whenever he caught sight of the magazines Dean failed or forgot to hide. It sent blood rushing to his cheeks whenever Dean gave him the look that meant he had accidentally made another comment with sexual connotations. It sent blood rushing down when a pretty girl-the type of girl Dean usually liked, in the type of place Dean usually frequented-gave him a smile and a wave.
He imagined words being spoken low and close to his ear, imagined hot breath on his neck and soft hands moving smoothly up his arms. He imagined fingers slipping under the collar of his shirt, sliding down to open it one button at a time, and bit his tongue hard to clear his head of the visions. Lust's touch left him aching for contact and yearning not to want.
And pride? Pride came when he first thought back on his Fall with pleasure. Pride grinned every time Castiel refused to regret turning his back on Heaven. Pride settled into every bone in his body and laughed as he embraced humanity.