Cas was staring up at the strange plant hanging above his head with a quizzical look. Gabriel had put it up the day before, muttering something about not hogging all of it for his and Sam's bedroom. Hearing Dean walk into the room behind him, he asked, "Dean. What is this plant here for?"

Dean looked up, and a tinge of red colored his face.

"It's mistletoe, Cas," he replied, shoving his hands in his pockets and scuffing a foot against the floor.

Well, that didn't explain much, and Cas only became more confused by the reaction it seemed to be having on Dean.

"What is it there for?" Cas asked.

Dean rubbed the back of his neck with one hand, glancing up at Cas through his eyelashes.

"Holiday tradition," he muttered. "You're supposed to kiss someone when you stand under it."

Cas took a moment to process the explanation, and then he smiled. He reached out for Dean, pulling him closer, and kissing him soundly on the lips. He might not understand what the purpose was, but he decided it was definitely a tradition he wasn't going to break.