This was originally conceived as a follow-up piece to 'The Cat's Kill Affair' (also available on this site and AO3), but all you actually need to know from that is that Illya is Jewish, but not religious, something which Napoleon only recently found out.
"What does this mean?"
Entering the office he shared with his partner, Napoleon Solo found himself fixed in place by a pointed question and an even sharper stare.
Napoleon's eyes flicked to the gift-wrapped box on Illya's desk, and then back to his partner.
"It's exactly what it looks like, a present."
"On December 16th? To what forsaken place are you about to send me for the next," Illya paused and counted on his fingertips, "ten days?"
"No place. At least, not that I know of…yet," Napoleon conceded. In this job, he'd learned not to make too many promises. "It's just, yesterday was the first night of Hanukah, and, well, I've made you celebrate Christmas with me for all these years."
"Oh, I don't celebrate Hanukah." Illya replied, rolling the 'H' into a richer, rougher sound that rumbled somewhere in his throat.
Napoleon felt distinctly off balance.
"Really Napoleon, Judah Maccabee and his followers were a gang of reactionary zealots; Hanukah is an insignificant festival, artificially inflated in prominence due to its unfortunate proximity to your Western Christmas and its capitalistic excesses." He shrugged, "What's to celebrate?"
"Alright, well, if you don't want this…" Napoleon made a move to grab the gift back off of the desk in front of him.
Illya caught his hand and held it. "No, no, I'll keep it." He smiled innocently up at Napoleon. "And, if you're still feeling badly about forcing your cultural hegemony upon me…"
"I'm, ah, not sure I would go that far…"
Napoleon felt Illya's thumb press into his flesh, rubbing firmly over the back of his hand. He was unsure if this constituted a promise of future pleasure, or a threat of imminent phalangeal dislocation. He chose to believe the former, but abandoned his argument in any case, cutting himself off with his own small, throaty sound.
Illya abruptly released Napoleon's hand, "As I was saying, if you're still feeling badly about forcing your cultural hegemony upon me, I'll let you take me out for Chinese, say, a week from tomorrow?"
Eight Days Later
"What kind of restaurant was it you said you wanted?"
"Napoleon, we are in Beijing, all of the restaurants are Chinese."
"Ah, so that's good then. I'm so glad everything worked out."
Napoleon couldn't quite shake the glum note from his voice, nor the feeling that everything had not, in fact, worked out. Given the current condition of Sino-American relations, their flights home, when they could get them, would undoubtedly be indirect. Even with the time change in their favor, he doubted they'd reach New York the next day, or even the day after.
Christmas Eve was half spent already, and, at this rate, rather than unwrapping gifts, they would be spending the upcoming day in wrapping up their mission— a tedious, exhausting mission that had spat them out deep in Communist China. On Christmas.
Napoleon sighed and kept walking. The streets were crowded. Though cars were rare, people rushed past on foot and zipped by on bicycles. Napoleon and Illya garnered a steady stream of looks from passers by. Pedestrians whispered to one another and peered at the agents with poorly disguised curiosity, tugging on their companions' coat sleeves so they too could get a good look at the gui lao. Napoleon, accustomed by habit and profession to blending into any social milieu, felt uncomfortably conspicuous.
Looking around, you would never guess that it was Christmas. There were no wreathes, no fairy lights, no candy stripes. Napoleon caught flashes of red— banners hung on doorposts, flags whipping in the wind. Whether calling down prosperity or rallying the peasant masses, they were nothing like the red and green decorations that dominated December in the States. Napoleon felt acutely foreign, and suddenly, terribly lonely.
If this was the universe sending him a Christmas lesson, he was reading loud and clear. "Hey Illya," he said, "I'm sorry if I ever forced my cultural hegemony upon you."
"Hmm?" Illya caught his eyes, scanned through the crowd around them, and then turned back to Napoleon with a smirk that softened as he spoke, "And I'm sorry that you're missing Christmas in New York."
"It's alright." As an agent, Napoleon was sure he ordinarily could lie with much greater authority. Not that it mattered much with Illya; his partner could usually see straight through him anyway, as he did now.
"You're allowed to be disappointed; I can see that it's important to you." He smiled, "Maybe I should have given you my gift early as well."
Napoleon was disappointed, of course he was, but, looking at it straight, it could certainly be a lot worse. They were alive; they were unhurt; they were together. He felt a little more holiday warmth already. "I can think of a few gifts you can share with me."
"Well, maybe not right here, but you never leave home without them."
"I see. I suppose you think you've been very good this year?"
"That's for you to decide."
"Alright then, we'll find out together. But first, we must honor an obligation as well as fulfill a true American tradition…"
"Napoleon, I was promised Chinese food."