"When humans want something really bad, they lie." Castiel decides the best way to get what he wants, in this case, is to lie. Destiel. T for cursing.
Why did I write this? Who knows?
"Dean..."
"Cas?"
"How does the human tradition of kissing work?"
That was not what Dean was expecting. He turned to Cas.
"When people like each other, they kiss. Sometimes it's more complicated. Usually, you can tell when people wanna kiss you. Sometimes, you fuck it up." He sounded like he was speaking from personal experience. He was.
"No." Cas suggested a sigh in the tone of his voice. "How does kissing work?"
"Like... How do you kiss someone?"
"Yes," Cas said.
"Why?" Dean asked.
"So that if I wanted to kiss someone, I would know how."
Dean was used to the familiar ping of jealousy he felt. He'd long since accepted what it was and what it meant.
"It's complicated," Dean explained. He began a vivid description of kissing, one that meandered and branched into options and styles- Dean had a lot of data to choose from.
He hadn't finished before Cas, who was listening attentively, interrupted him.
"Perhaps it would help if you could give me some practice."
"What do you mean?" Dean asked, trying to keep the sound of a virtual blow to the lungs out of his voice, knowing EXACTLY what he meant and not believing it and Castiel did not just ask Dean to kiss him, no way.
"You could kiss me, to show me how to kiss," Cas said.
Dean was too distracted by Cas's words to hear his funny enunciation.
"You got someone you're trying to impress?" Dean joked, accidentally sending himself into a fit of jealousy. Oops.
Cas inclined his head and smiled.
Dean smiled too- a sugary, sour smile.
"Will you kiss me, then?" Cas asked. "To teach me." It was like he felt the need to clarify the purpose of this kiss.
Ahh, what the hell. "You asked," Dean muttered, standing up, crossing the room, and seizing Cas by the trench coat collar with one hand. He leaned down and pressed his lips against Cas's, intending to do it roughly and quickly but not exactly following through with that.
Dean relaxed into the kiss a tiny, tiny bit, but that was a mistake, because suddenly he was pressed against a wall with fingers carding through his hair and a mouth still against his and no idea how he got there.
Cas finally broke away from Dean, and Dean did his best to catch his breath.
"Son of a bitch," Dean said. "Cas, what the fuck were you going on about, needing practice?"
Cas said something very unexpected. "You said when humans want things very bad, they lie," Cas explained. "I lied."
"Oh," said Dean, and again, louder, as the first part of Cas's sentence hit him- "OH."
Cas seemed to be awaiting judgement quietly, albeit with a smug sort of look in his eyes.
"You know, Cas," Dean began casually, "sometimes, you don't need to lie."
And he reconnected their lips.
When they finally broke apart, Dean asked, "Who'd you wanna impress?"
Castiel almost rolled his eyes. "You, Dean."
"Consider me impressed."
Okay, so... uh, not much experience with kissing and/or writing about it. None, actually. Here's the result.
Note from your tentative and doubtful author: In these kinds of situations, I'd suggest you do not lie or avoid certain truths to manipulate people, but that would make me a hypocrite.