[Kimetsu no Yaiba] The Flame and His Sun

Title: The Flame and His Sun
Fandom: Kimetsu no Yaiba / Demon Slayer
Pairing: Rengoku Kyoujuro / Kamado Tanjirou
Words: 1.111
Completed: 2023/03/26
Summary: The last thing Rengoku remembers were maroon eyes, rich as the summer sunset but shining ever so brightly like stars found in the deepest of the night. These orbs, the most beautiful gems Rengoku has ever seen during his short stay on earth, were filled with grief and sadness.

And tears.
Oh, the many tears.
Links: AO3 & FF.net

The last thing Rengoku remembers were maroon eyes, rich as the summer sunset but shining ever so brightly like stars found in the deepest of the night. These orbs, the most beautiful gems Rengoku has ever seen during his short stay on earth, were filled with grief and sadness. 

And tears
Oh, the many tears

Rengoku’s heart aches; in his final moments, every fiber of his being screamed for him to reach out to the boy and pull him into a tight embrace. He curses at his own weak and broken body, using the last of his remaining strength to talk to the young demon slayer instead, though words did little to convey the fierce passion burning in his soul.

Perhaps Rengoku should be frightened of how effortlessly the boy has wormed his way into his heart. What started as simple curiosity soon bloomed into mutual respect for the fellow demon slayer and lastly thrived into admiration. These few hours spent on the train were enough to ignite Rengoku’s very core and the flames burning in his heart whisper the same word over and over again: protect, protect, protect. 

Rengoku never failed a mission before and he didn’t plan to start on that fateful day. He kept the boy safe with his last dying breath, regardless of his inability to kill the demon in the end. All things considered, there should not be any room left for regrets on the Hashira’s part.

And yet he still yearns

He longs to be back right next to the boy whom he has left behind with a shattered heart; to be the one at his side, accompanying him wherever he goes and keeping him safe

(Oh gods, I never asked for much, but please protect him.)

A curse escapes his lips as a jolt of pain runs through his body. Even in death, he isn’t spared the pain once inflicted on his mortal body; a constant reminder of his own weakness and failure. Rengoku never has been an overly religious person; he doesn’t believe in anything remotely resembling the afterlife – and yes, he is perfectly aware of the boldness of his statement, considering he himself is living through it right now – nevertheless, he can’t help the wishful thoughts popping up in his head that he might have been able to meet his mother just one last time.

Did he make her proud, he wonders, doubt continuously nagging on his mind despite the ever-constant echoes of the young slayer’s desperate cries, still all too fresh from recent memory. Yes, he has saved all 200 passengers on the train, but was that really enough? Has the life of Rengoku Kyoujurou been sufficient in the face of the power gifted to him? 


Rengoku’s vision shatters and white noise fills his ears. The darkness, a once familiar and strangely comforting companion during his wake in the afterlife, slowly fades away to make way for gentle, yet incredibly warm rays of sunshine. He relaxes, letting the sun embrace him in a fashion he can only describe as coming home. 


All at once, his eyes fly open and everything is just so bright, bright, bright. He grunts, visibly confused because why is one half of his vision gone?? and in a sad attempt to speak chokes on his saliva, sending painful waves through his exhausted and severely broken body with each cough.

“Ren–” A sob muffles the young men’s voice and then Rengoku finally sees him

The boy, the young demon slayer with burgundy eyes and the unmistakable burn mark on his forehead. 

Kamado Tanjirou.

His sun.

“You–you’re—” Tanjirou hiccups, unable to say more than one word before another sob catches them in his throat. His eyes are puffy and traitorous marks of dried tears hug his ashen cheeks. 

Oh, my boy.

He needs to reach out, to hold Tanjirou’s hand firmly in his own and shout from the top of his lungs that he is here, that he is alive, yet his body refuses each and every one of his wishes vigorously.

Please don’t cry, my boy.

Someone must have entered the room because Rengoku faintly hears a gasp from afar. “Ko-Kochou-san!”, the person calls for the Insect Hashira,  “Rengoku-san is awake! Kochou-san!

Everything from this point on happens in a blur, with Rengoku in the center of the hurricane named Shinobu and her army of helpers. The Insect Hashira frantically hovers over him, poking not only his body but also the man himself with questions. His voice is still hoarse, possibly from the lack of use (just for how long has he been asleep?), thus posing quite a challenge for the Flame Hashira to answer her questions. 

At one point during the examination Rengoku tries to sit up, but the immediate pain punches the air out of his lungs and sends the man into another agonizing coughing fit. Before any of the medical caretakers around him can react or even intervene, Tanjirou beat them to it and finds himself at Rengoku’s side in a flash, grasping for his hand and whispering calming words to the Hashira. Rengoku, still coughing and hurting, leans into the touch and moves his hand ever so slightly, just enough to make it easier for the pair to intertwine their fingers. 

For a split second, Koucho’s ever-present mask slips, and her features vary from astonishment to wonder and eventually to understanding. She sighs, shaking her head with amusement at the pair in front of her, and claps her hands to gather the attention of her staff. From here on the Insect Hashira quickly wraps up the check-up and announces that it’s going to be a long and bumpy road to recovery, but for now, the Flame Hashira was out of the woods. 

“Oh, and Rengoku-san?” Kochou stops right in front of the exit and turns to her patient, a smile plastering her face that could freeze hell over. “I’m going to say this only once: Under no circumstances are you allowed out of this bed until I clear you, understood?”
To her amusement, both demon slayers gulp, although only one of them is able to nod rather enthusiastically. 
“Rengoku-san?” She asks one more time, only satisfied once she hears a slightly panicked “Y-yes, ma’am. Understood!” from the man.
Her eyes move to Tanjirou and she notices their hands, still linked and holding onto each as if there were no tomorrow. She can’t help but giggle and mouths ‘Take good care of him for me’ to the boy, whose surprised yelp causes the woman to laugh whole heartily. 

The blooming blush on Tanjirou’s cheeks is rather adorable, to say the least.

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