Notes: This one is set nowhere in particular, but I'm watching season 5 right now, so I suppose it's safe to say that it could be set somewhere in season 5. You'll probably see it as slash and I don't blame you. Basically just Dean and Castiel developing feelings towards each other.

Summary: Castiel has some questions regarding the human side of him. Questions about Dean. He hopes Sam can help him.

Feedback: Pretty, pretty please.

Disclaimer: Not mine. If they were, I'd make Destiel canon. You know I would.

What Makes Us Human

"Sam?", a soft, quiet voice. Unsure. Hesitant. Sorrowful.

"Yes, Cas?"

Sam looked at the angel with a smile. Castiel was obviously uncomfortable, almost fidgeting in his seat. Sam didn't think he'd ever seen Castiel looking so nervous.

"I have a question regarding human nature," the angel stated finally, his voice not louder than a whisper.

"I don't know if I can help you with that, Cas," Sam laughed bitterly.

"Oh," the angel said sadly and dropped his gaze to the floor. "I guess I'll be leaving then."

"Wait!"

There was a small flutter of wings, but Cas didn't disappear. He was still there, still nervous, still uncomfortable.

"Just because I don't know doesn't mean I'm not gonna try," Sam added cheerfully. "What's your problem?"

Castiel sighed heavily and rubbed his face in a very humane notion. Dean was really rubbing off on him, Sam thought.

"I have been having these... feelings... lately," Cas said, very unsure.

"What kinds of feelings?"

"I'm not sure exactly. There are a lot of different symptoms, but I seem to be feeling them around your brother."

Sam laughed softly. "Does it kinda feel like you want to punch him?"

Castiel cocked his head to the side and frowned, giving the question some serious thought. "No, I don't think so."

"Do you sometimes want to slap him when he's making those same lame jokes over and over again?"

The angel cocked his head some more. "Jokes? I didn't know Dean made jokes. But I guess the answer is no, again."

Sam smiled then. "Okay, so why don't you describe to me what you feel. Or at least try to describe."

"Like I s-said there are different symptoms, so I guess it's possible that these are different feelings," Cas stumbled upon his own words. "But I feel... I feel", Cas said very slowly, as if tasting the word on his tongue. "I feel pain in my chest and abdomen, when he's hurt. Like I can't breathe. Like something is tearing at me from the inside."

Sam raised his eyebrows. Well, he didn't expect that.

"I also feel this weird kind of lightness when I meet him. When we talk, I feel like I need to look at him all the time. And when we don't talk, I wish I could talk to him," the words came faster now, more sure, as if Castiel wanted to get all of them off his chest as soon as possible. "But then there's this different feeling. When I do see him and we're talking and I have nothing to say, I want to disappear. I often do. And then I don't know why I did that. And then when we finally meet again, I just want to touch him. But when he touches me, I feel my knees getting weak."

He looked up at Sam with big puppy-like eyes. "What are those feelings, Sam? Can you explain them to me?"

Sam looked him in the eyes and smiled broadly.

"Yes, I can."

"So, what are those, Sam? What is wrong with me?", Castiel sounded frustrated now, impatient that Sam didn't answer him immediately.

"It's just this one thing, Cas. The one thing that makes us human."

"Which is?", the angel's voice was even more impatient.

"It's love."

The End.