Hate the sin not the sinner

Title: Hate the sin not the sinner
Pairing: Castiel/Dean
Rating: G
Warning: Spoilers for season 4. Angst
Word Count: 386
Notes: 1- The title is taken from the song Sin sin sin - Robbie Williams.
2- I'm Italian, so this fic was originally written in Italian. During translation I tried not to change anything, and if there are any grammar or spelling mistakes, let me know.
Disclaimer: I do not own Supernatural or its characters [dammit]. They belong to Eric Kripke.
Prompt: Castiel/Dean: wings

"They're black."
"They're white, Dean. Trust me. They're mine, I'm supposed to know what color they are."
"On Earth we say black. I don't know if up there everything is upside down, but when I saw them for the first time they were black."
"Shadows, Dean. Have you ever heard of them? A shadow is an area that direct light cannot reach because an object is obstructing its path. The ones you saw the first time we met were just shadows. If I showed you the real ones, you'd be blind by now."
"That's so kind of you."
"Are you making this conversation just to feel like a complete idiot, or to pass the time?"
"Teasing you is my favourite hobby, you know. Anyway, our friend is arriving. Wait for me here in the car. If he sees you, he won't say a word, he'll make you angry, you'll electrocute him with your pure white divine light, and we'll waste an opportunity."
"I do not electrocute. I purify."
"Yeah, yeah. Whatever."
Dean was already outside the car, stepping towards the house. From the Impala, Castiel was following him with his eyes.
Fence, stairs, porch, door. He was in. Half an hour passed. The angel could feel the presence of the demon; weaker, but still there.
Winchester or not, he decided to go in. With his best angel's trick, he teleported himself into the living room.
Dean was on the floor in front of the demon, puking. The demon, or what was left of him, was unconscious, sitting tied in the middle of a seal.
"I-l did it again. I tortured a soul and I got a kick out of it."
He was trembling, shaken by his retches.
Castiel entered in the seal and purified the body. Then he looked at Dean. Man was such a fragile creature. The most beautiful amongst all the creatures of the Lord. He felt so similar to them, full of doubts and uncertainties.
He helped Dean stand up and held him while they returned to the Impala.
"Castiel?"
"Yes, Dean?"
"Do you think I'd have my own pair one day?"
"Your own pair of what, Dean?"
"Wings." Dean was crying.
"For sure, Dean. The most beautiful wings in Heaven."
The Winchester smiled painfully.
"Black as the Impala?"
"...black as the Impala." said the angel, whispering.