Word count: 400-ish

Genre: AU

Rating: worksafe

Prompt: Destiel, highschool AU

"What is the velocity of an unladen swallow?"

Castiel looked up from his notes, eyebrows furrowed as he focused on Dean's expectant expression.

"Pardon?"

"What is the velocity of an unladen swallow?"

Castiel's frown deepened and returned his attention to his notes, now flipping through his neatly organized equations and calculations at a pace which made Dean suspect he knew them well enough by heart to not even need to really look at them. "What chapter are you at? I don't recognise that from any of our books."

Dean raised an eyebrow. "You've read all of our books already?"

Castiel nodded, eyes still cast downwards. "Naturally."

Dean only just managed to keep his mouth from falling open. Shaking his head, he sighed. "I should have expected it. You're the biggest nerd I've ever encountered, Sam included. And that's sayin' something."

Castiel cast a quick glance at Dean, eyes narrowed. "Perhaps you shouldn't disregards other people's wish to learn, when you own disability to respect the classroom rules which has caused both our current situations."

Dean shrugged. "Can't say I'm too sad about the current situation myself." He only just managed to not wink, reminding himself that Castiel was a socially awkward person/being who probably wouldn't get what he was trying to say.

Speaking of not getting it…

"It's a line from a movie, by the way."

"What is?" Castiel didn't look up from his notes.

"The velocity of an unladen swallow. It's not from our books, it's Monty Python."

Castiel's page-flipping came to a halt. Blue eyes turned from maths notes to regard Dean, sending that now-familiar jolt of electricity down Dean's spine. "What is Monty Python?"

Dean hid a grin. Hook, line and sinker.

"Oh hell no," he exclaimed, making sure to sound appropriately aghast. "That's just not right. You can't go through life and not experience the genius of Monty Python." At seeing Castiel's quizzical expression turn sceptical, Dean pursed his lips. he was immediately rewarded when Castiel's eyes flickered down to Dean's mouth, the shadow below his adam's apple moving subtle as he swallowed.

"I'm serious man. It's about time you get some real education. Come on!" He motioned towards the living room.

Castiel looked down at his notes. "Dean, I'm supposed to help you study…"

"Cas, you do want to know that the velocity of an unladen swallow is, right?"

Castiel hesitated, then nodded.

Dean couldn't help grinning openly this time.