A/N: Inspired by the Taisho Whispers and Rumors Section for Giyuu in the English Translation of the Corps Record Book. Specifically the first half:
Giyuu's haori jacket suffers damage during the final battle. Nezuko skillfully mends. Unfortunately, not much remains of the original fabric, which held precious memories for him. Nonetheless, her repairs nearly restore it to its former apperence. Moved, Giyuu begins sending her countless presents (kimono, Western clothes, hair ornaments, jewels), thereby earning Zenitsu's animosity.
Giyuu arrives in front of the Kamado household, an isolated cabin in the mountains. With the wrapped gift in his left hand, he marches forward.
On the other side, from the corner of Nezuko's eyes, she sees her former benefactor. She drops the vegetables she was washing for tonight's dinner and runs towards him.
When Nezuko jumps and hugs him, Giyuu briefly loses balance, but recovers just as fast. Nezuko squeezes him during the embrace. In response, Giyuu leans forward and tilts slightly, letting his head rest against the top of her head for a beat.
A moment later, Nezuko lets go, and they both take a step back. Familiar with this song and dance and in complete silence, Giyuu hands the wrapped gift he's holding, and Nezuko accepts.
One blink later, they curtly nod at each other.
In another blink, Giyuu runs, already covering about half the distance between where Nezuko was standing and to the back of the cabin. The smoke that was wafting drew him in.
Zenitsu walks out of the cabin and stands by Nezuko's side. He shoots a dirty glare at the former water pillar.
"Do you really think it's like that, Zenitsu-san?" Nezuko asks, quirking an eyebrow up when she turns to look at him.
Even without hyper-sensitive hearing, she can hear Zenitsu's teeth nash, muttering about the one-sided rivalry.
"It's not what you think, Zenitsu-san," she says, smiling with a glint of mischief in her eyes.
"How -" Zenitsu stutters. From his eyes, it's as plain as day. "How can you be so sure of that, Nezuko-chan?!"
Nezuko grips the wrapped gift with her left hand and starts to head toward the same direction Giyuu went off to. "Over here," she gestures, "you'll see what I mean."
Zenitsu puffs his cheeks and pouts for a moment. Nezuko stares back at him, waiting. Another beat passes before he sags his shoulders and ultimately decides to follow her. The two walked together, side by side, in silence and stood at the corner of the cabin, out of view.
Nezuko sets the gift by her feet. She then takes her right index finger to her lips and uses her left index finger to point to her ears. Zenitsu stares for a moment and scrunches his face, skeptical. But another moment passes before he decides to indulge in his Nezuko-chan's wishes.
From behind the cabin, Zenitsu could see the former water pillar was chatting with the only person working behind the household today, Tanjirou. The former water pillar listens to him and watches Tanjirou char the morning's freshly cut wood, preparing for the tomorrow's sales.
Zenitsu then turns back to Nezuko with a raised eyebrow. Nezuko shoots back with a sharp glare and uses both hands, this time, to point to her ears. He scowls in return but does as he's told. Zenitsu perks his ears, using his sensitive hearing to his advantage.
And then he hears it.
The former water pillar was laughing. If he were to put it to an image to describe the sensation, it reminded him of a warm pond, sitting in the sun in the forest. A quiet scene that holds a deep feeling of tranquility.
There's a soft crinkle in Giyuu's eyes as Zenitsu watches the former water pillar cover his mouth, trying to hide his teeth while he chuckles. Tanjirou, even while preparing tomorrow's charcoal, finds the time to take his hand and move Giyuu's hand away from his face. He can catch Tanjirou's slightly whine at Giyuu, saying "stop that." Despite this, there's still a lightness to his voice.
The tone was so familiar. It was one that he frequently heard in his dreams with Nezuko-chan. The same tone he frequently heard in passing the many couples hanging around on the outskirts of town or in crowded restaurants in the busy cities as he returned from his many missions as a Demon Slayer.
It finally clicked. They're flirting.
Even without listening too carefully on what exactly was being said. The undertones in their voices were more than enough.
Zenitsu quickly catches Tanjirou looking up earnestly at the former water pillar with a faint blush across his cheeks. The former water pillar takes his hand and pets the top of Tanjirou's head. A smile flashes across his face and the early morning sun casts its warm glow on both of them. Looking at them reaffirms that familiar mental image he had just moments ago. Zenitsu turns his head looking away, and tries to stuff the guilt of intruding on a private moment between them down his throat.
He then turns to Nezuko.
"I understand now, Nezuko-chan."
She finally looks away, tilts her head, and giggles. "You know, Zenitsu-san," she starts.
Zenitsu doesn't know exactly what else to expect after this. There isn't that same feeling of dread that crawls up his spine and up his neck in the same way when he was a demon slayer out on a mission. Yet, he finds the weight in his feet shifting uncomfortably. Despite this feeling, he allows her to continue.
"If you tell Uzui-san that Onii-chan's oiran days never ended, he bursts out laughing."
Zenitsu's eyebrows twitch at the mention of the former sound pillar, but his eyes focus on the gift by Nezuko's feet. He glares at it with the same intensity as he did when the former water pillar first arrived. There's a long and drawn out stare before the feeling he got from watching the two really starts to sink in. Finally, he softens and smiles at the neatly wrapped package by Nezuko's feet.
He crosses his arms and chuckles for a bit before finally responding. "I suppose they haven't, huh?"
If you made it to the end, thank you. It's all I could ever ask for. If you enjoyed reading it as well, then, that's simply a bonus.
This story can also be found on Archive of Our Own under my alternate handle, purenguyening. Please see the AO3 version for full attributions.