It started as a prank they both unwittingly played on each other, not expecting their other half to get the exact same idea at the exact same time.
In hindsight, Osamu should have realized as much when he'd bumped into Chuuya in the hundred-yen shop that day, clutching the same pair of joke glasses he had his eye on before ducking away from view. To say he'd been caught off-guard on receiving the exact thing he'd bought for the gift exchange event was pretty much right, loathe as he is to admit it.
He didn't know whether the chibi's snickering behind his back should have annoyed him or not, but he let it slide, like all other things. It wasn't worth his attention in the long run.
This inside joke they shared extended to a few more occasions throughout the years— birthdays, holidays, anniversaries, and other random times, for no other reason than they both felt like it. Paydays, obviously. Some Wednesdays, just because. Every May 3rd, too, to commemorate victories that came with a price. It was how Chuuya mourned his men, and Osamu is only willing enough to acknowledge that.
Unpacking his sparse belongings now in his new dorm brings those memories back, and the sight of the assortment of oddities he'd accumulated over the months and couldn't bear to throw away, makes him hit the nearest, dingiest alleyway bar in the city that same night. While Osamu had promised to never drown himself in his sorrows again, he wants to be numb, just for tonight.
He is offered a glass of pink liquid by the grumpy bartender who judges him a little too early than is polite. The light taste of fruit lingers on his lips and tongue like too-long summer afternoons that go on for days on end, before the full force of the alcohol hits him like a thunderstorm in the night. Nobody pays him any mind, but a small box of pull-up tissues appears beside his empty glass— an unexpected kindness, really, for someone with too little tact for his job.
Osamu spends his first paycheck from the Agency on a bottle of new watermelon wine, and has it delivered to an address he has long-memorized by heart. An imported version of it appears on the Agency's doorstep a few weeks later, and he finds himself in muffled laughter as Yosano swipes it off the table at once and excitedly takes a swig for herself.
Their tradition continues thus for a few tentative months that extend into years, like an unspoken agreement that needs no discussion— must merit no discussion, lest the discreet understanding between them is lost and their fragile connection is severed. "No one must know," Osamu warns in an elaborate code he sends with a scented candle for next Wednesday. The note that comes back with the exact same item but with a different price tag is written simply in bold words: "Dumbass."
At one point, Atsushi marvels at the growing collection of souvenirs that line the shelves of his dorm room: a tacky snow globe, a faded fart cushion, a figurine made out of used staples, some obscure idol's cheer towel, and rolls and rolls of bandages, among others. The empty bottle of wine hidden behind them all still smells faintly of summers past, and no one else knows how Osamu deeply relishes every night the musty but sickly-sweet scent it has now become.
Christmas Eve this year is a little warmer than usual, though it doesn't stop the children (and man-children) from lamenting the late arrival of snow for the week. Everyone is dismissed early for the day to keep them from being insufferable, but it only makes them wonder if Kunikida has finally managed to get a date for the holidays, for once.
Osamu excuses himself at exactly five o'clock, making his way to the outskirts of the city before throngs of couples fill the streets at night. A simple postcard not unlike the one he had just mailed yesterday is in his breast pocket, bearing only an address he knows by heart, written in a scratchy penmanship dearest to him by far.
He makes it to his appointment just in time, but Chuuya scowls at him at the entrance, anyway. "You're late, mackerel."
A typical admonishment by the only voice that warms his heart like no other. "You're early, slug."
They ride the elevator to the rooftop and climb the ladder up the old water tank. The 360-degree cityscape is a gradient of orange to red to purple to deep blue, and the thin December air still carries the warmth of July's summer, though they are both quick to realize that the surface they chose to sit on is made of thick, insulating material.
Chuuya presses a tall, chilled can to Osamu's cheek. "Drink." A crack of a smile forms there, and it's the only sight he needs to see.
He does as he is told, savoring the malty yet refreshing taste of the watermelon beer as it goes down his parched throat. His partner has already swiped his offering of a no-doubt inferior version of the same beverage, downing the entire thing much faster than he would a regular glass of water. He pays the price for it, of course, with consecutive, choked coughs and colorful expletives that describe well enough how disgusting that drink was.
Osamu only laughs heartily at his expense for it. "You reap what you sow."
"Shut up," Chuuya snaps, opening a second one anyway. This time, they clink their cans together in a toast before chugging those down, too.
They quietly finish the two six-packs they brought between them over the next couple of hours, just like that. Chuuya is normally more boisterous when drunk, while Osamu is the more moody, quiet one, but they often manage to meet in the middle and temper each other's behavior, like twin peas in a pod.
Maybe calling them seeds from the same watermelon would be more apt, considering their unexpected shared newfound taste for it— when fermented and bottled or canned, anyway.
"Hey, Chuuya," Osamu languidly whispers into his ear, as they lie together to watch the moving stars, the warmth from the alcohol protecting them from the now-chilling night air. "I think I know what to get you for Christmas next year. What do you want engraved on it?"
He gets a weak but sensible slap to his face for it. "Not a chance, dumbass." Chuuya's always been the more reasonable one between them both, despite having instigated that prank all those years ago. But then again, it was Osamu who allowed it to go on for as long as it has now.
So he only smiles at this, patiently awaiting for his partner to come around— and he does. "Today's date."
"This day, this hour, this minute?"
"This day, this hour, this minute— wait, what are you making me say?!" The sudden jolt of surprise as Chuuya sits back upright immediately loses its momentum, and Osamu rolls over to cushion his fall. He holds the struggling chibi close to himself, relishing with every deep inhale the sweat and the must and the sickly-sweet fruit breath he's come to love.
"Got you," he doesn't say for now, but he swears to do so, this time next year. Until then, the next few gift exchanges between them will be more fun, to say the least.