Work Text:
There's a sharp hitched sound pierces the darkness of their room. Zenitsu is aware of that. Through his own darkness he listens. The sound slowly turned into a small sob. A sniffle quiet enough to hold, but loud enough to his ears.
The calm thrum beside him shifts into a more erratic sound, twisting and turning the formerly steady rhythm into something akin of restlessness. Nightmare.
It's Tanjirou.
Zenitsu turns to lay on his back. His own breathing getting heavier under the gravity and his throat automatically produces a loud snore. He knows he snores loud, Tanjirou told him once and Chuntarou often complained about it (courtesy of Tanjirou's kindhearted translation), and he often find himself listening to his own snores--which is annoying, but it's not like he can do something about it.
"Ah--Zenitsu..." a soft, shaky voice is heard before he feels his body's being moved to lay on his side, "There, it stops."
Stupid. And here he think Tanjirou will use the opportunity he so generously offer to cry for a little bit.
More hearing than feeling, Zenitsu knows that Tanjirou's gently patting his side now, probably to calm him and prevents him from laying on his back again. Seriously, who do you think the one who needs to calm down?
But after a few pats on Zenitsu, Tanjirou's sound is also getting relatively calmed down. He still can hear the sniffles, but there's also a few chuckles here and there that makes the sound lighter. Zenitsu just hopes it's not his ugly face that prompts the chuckles.
There is a bit of steady moment in which Zenitsu thinks Tanjirou is already going back to sleep, but then a few rustling sound is heard and soon Tanjirou is slipping out of the room. Then, the erratic sound is coming back at full force. The sobs' getting louder now that Tanjirou thinks he is out of hearing range. Zenitsu sighs.
He waits for the sound to get calmer before opening his eyes and searches for Tanjirou. Said boy is sitting on the veranda outside their room. Zenitsu tiptoes quietly as not to wake Inosuke or startling Tanjirou. But damn his smelling sense, when Zenitsu slides the door open, Tanjirou is quickly to regard him with a smile.
"I'm sorry. Did I wake you up? Am I too noisy?" Tanjirou asks in concern.
"I'm just awake myself," Zenitsu said. "Cannot sleep?"
"Yeah. Don't mind me, though. Go back to sleep when you feel like to."
Zenitsu hummed. Naturally he needs to sit down with him when he's talking that way. He yawns and leans closer to Tanjirou, closing his eyes to listen to familiar gentle melody beside him.
"It's rather chilly," Zenitsu said.
"It is, isn't it? It's almost winter."
I mean your sound. But Zenitsu doesn't let that out. It's not the first time Zenitsu subconsciously witnessing Tanjirou having a nightmare. It doesn't come often, but it's not a rare occurance, either. When he was wounded or hurt, Tanjirou would sobbing and whining in his sleep. The nightmares would come often at that kind of time. It's like since Tanjirou always tries to be so strong on daily basis, the nightmares feel intimidated and thus only come to him when he is in his weakened state.
Zenitsu knows what kind of nightmare Tanjirou has, too. Tanjirou once told him about the tragedy he had to witness prior being a demon slayer: the massacre of his family that left him only with Nezuko who turned into a demon. Then there's also Rengoku-san's death, too. Tanjirou has seen so many deaths in such short period of time, and he's always trying to bear it alone. No wonder all of those miseries he put on chokehold at day bled into his dreaming state at night. And it's not as if they as demon slayers had that many nights spent on sleeping, either. They only sleep at night when we are wounded or in between missions. The stress must be accumulated, even for someone as bright as Tanjirou.
Zenitsu never actually asks, though. Because Tanjirou always acts like he doesn't want anyone to know, not even Nezuko. So Zenitsu just sit with him. And wait.
"What's that song?" Tanjirou suddenly asks.
"What song?"
"The one you're humming," Tanjirou said, "You hummed that songs quite a lot lately. I've never heard that song except from you."
Zenitsu hummed some notes he unconsciously sang. "That one?"
"Yeah. It's so beautiful. Like a lullaby."
"It is a lullaby."
"Oh? How do it goes? I never heard the lyrics, though?"
Zenitsu pats his thigh. "Come here, then. I'll sing it for you."
There's a small sound of hesitation rings from him, but then Tanjiro crawls to him and put his head on Zenitsu's lap. The casual way Tanjirou does that makes Zenitsu smiles. Sometimes Tanjirou is so obliviously intimate to a fault.
He sings parts that he remembers the most. Parts that always replaying in his head whenever he hears Tanjirou's sound or generally thinking about him. Just like what Tanjirou did to him earlier, Zenitsu also gently pat Tanjirou's side along the beat of the song.
O, a gentle sound that makes me want to cry
No matter how painful
Move forward, move forward, keep going on
Cut off that despair.
After that he stops singing and turns back to humming the rest of the song. He doesn't know the rest of the lyrics. Or more like he hasn't thought about it yet. Tanjirou is awfully still the whole time and when Zenitsu receeds to a humming, Tanjirou throws him such an unusual look it makes Zenitsu face feels warm.
"It's such an unusual lullaby. I thought it would be about rabbits or chickens."
"Well, just be grateful that I'm trying to help you sleep by singing you some lullaby here!" Zenitsu jabs at Tanjirou's side and makes the latter gasping his laugh as an effort to keep quiet. They're involved in some jabbing battle for a while before Tanjirou acknowledges that he will never win againts the speed of a Breathe of Thunder user.
"But it's still a beautiful lullaby, and Zenitsu's voice is so nice. What's the name of that song?"
Zenitsu ponders this for a while, "It doesn't have a name yet. It's a song that pops up in my head whenever I heard Tanjirou's sound, after all."
The unusual look comes back, now with a light clanking sound that awfully like the sound from his hanafuda earrings but isn't. Zenitsu watches in amazement when he sees the color red slowly blooms on Tanjirou's cheeks and nose and realized a tad too late that his face, judging from how warm he feels, is also mimicking the gestures.
"Um, then Zenitsu will sing that lullaby for me only? Is Inosuke also get his own lullaby?"
"Eh, Inosuke's sound is mostly a roaring sound, though. I don't think anyone can sleep with that kind of song."
Tanjirou grins, then, a big one with rows of his white teeth on display. The clanking sound multiplied, like series of wind-chimes blown by the wind on a sunny day. "Would you mind sing it again?"
And that's when Zenitsu realizes that the nightmare has passed for that day.
Zenitsu nods and starts to pat Tanjirou's side again. Tanjirou's making a happy sound while he closes his eyes, a big, eager smile plastered on his face.
"The lyrics are not completed yet, so I won't sing the whole song."
"Would you teach me the song when it's completed? I want to try to sing it, too."
"No."