Dean turned away from the other three for a minute to refill his coffee mug, and blurted out something he'd been wondering for a while. "Hey, Cas, I don't think we've ever seen you blush."

Sam sat up straighter at the table, watching Cas and Jack in a new light. "Wait, can angels even do that?"

"Not really—" Cas tried to say, but was interrupted by Jack, who was beaming innocently.

"Of course!"

Dean chuckled as he sat back down. "You sure you know what blushing is, kid?"

"Yeah! We do it with our wings. Castiel covers his face constantly."

"... When does he do it?" Dean asked, sharing a quick glance with Cas.

"Whenever you tease him. Or smile at him, like right now."

Cas began to look uncomfortable, and Dean couldn't help a laugh.

"I'm not—!"

"He's super hiding himself now."

"Jack!"