Fear.

It's a terribly icy feeling that had festered in Muzan's chest for years. Fear that his mission was pointless, that he'd never meet his goal, that another like Yoriichi would rise up to kill him. That his own demons would try to revolt against their master.

He spent years trying to quench his fears. Years spent cutting the head off anyone who dare pose a threat, stomping down his foes and challengers, inciting fear, and planting certainty...

And yet... it did nothing.

He stood no longer on his pedestal, on the same playing field as gods - he stood as a lowly human, scrambling to hold on to life. That lofty height that he spent so long climbing for came crashing down around him, filling his ears with his own angered screams and desperate thoughts.

The girl's sword burned as it severed his flesh, leaving his wounds struggling to heal through the cauterized flesh. The boy's fires seemed to try and eat him alive, like some sort of retribution for the human blood he'd forced the boy to devour.

He hated it. He hated that no matter where he turned or what he did, they were there to thwart him. Everyone, everyone that he'd failed to kill was here now, making him regret it.

The poison burning in his blood was doubtlessly Tamayos. Yoriichi's students lay spread before him covered in blood and determined to slay him. The girl was leading the charge with her pink fire, using her own demonic gifts against him.

All he had failed to dispose of now rose in tandem to kill him.

Poetic, really.

As Tanjiro's flames engulfed him once again Muzan cursed his own arrogance. He'd raised the demonic child to be everything and more, and now his creation had turned to destroy him. In another time he would've mused that this was the world's karma coming to get him - but he knew that such things didn't exist.

... wait... what was that twisting his cells and curdling his blood.

As if to prove otherwise, the world deemed it time to raise the sun. Golden light streamed out of the horizon and Muzan nearly screamed.

No...

no.

Muzan writhed and snarled, lashing out as he tried to flee - he had to get away - had to survive.

He couldn't escape as he had with Yoriichi, Tamayo's poison ensured it. He had to fight his way through.

He took a step to flee and found Tanjiro's claws sinking into his legs, making him topple to the ground.

"THE SUN WILL KILL YOU, BOY!" he threatened as he tried to kick at the boy's face.

"Good."

That was the hiss that barely reached Muzan's ear and never registered. The boy burst into his blood demon art - setting his golden flames to Muzan's skin that devoured him like a pack of wolves. Nezuko hissed as she set her hands on Muzan's neck, fitting him into a chokehold as the fires of her brother left her untouched.

"NEZUKO! TANJIRO! THE SUN IS RISING - " Kyojuro tried to warn as he shakily stood and raised his sword.

"GET THE FUCK AWAY!" Sanemi yelled, his eyes flitting from the brilliant golden sphere in the sky to the two demons pinning down their fallen Lord.

"NEZUKO!" Zenitsu cried desperately.

"THE SUN WILL KILL YOU DUMBASS!" Inosuke roared charging forward.

Nezuko kept a firm grip on Muzan who thrashed and screamed in fury and desperation but could not break out of their grip. Slowly, Nezuko looked over to Tanjiro and met his eyes.

"Love you," Nezuko breathed as the first rays of sun peeked through the rubble and slammed into her face.

It was agonizing - like fire under her flesh, curdling her demonic blood and setting her skin aflame. She thought for a moment she had started to scream - but the inhuman screech that attacked her ears was the result of Muzan. As the sun brushed against his skin the Demon Lord contorted and screamed in such fear that it could've been comical had Nezuko not been holding back tears from the pain.

She desperately tried to keep a firm hold on Muzan but her hands had started shaking as it felt like every cell in her body spontaneously started combusting. She was a demon now - no doubt, and it seemed like she was about to die a demon's death.

No time to mourn - no time for regret. If she faltered now Muzan could escape and -

Someone kicked her away. The blow was so sudden and blind-sighted her so badly that it ripped her from the combat and threw her into the shadow of a nearby piece of rubble. The shade was absolute respite from the agony but Nezuko's adrenaline was stil pumping. She jumped to her feet to fight whoever was trying to save Muzan - but found no new enemy before her. There was only Tanjiro, looking at he as he held Muzan down.

Nezuko could've killed him. 

"TANJIRO!" she yelled lunging forward until Giyu ran over, and with his one remaining arm, held her still. She could've thrown him aside, could've shoved him off - but he was already so weak that she hesitated. A wrong move could kill the frail water pillar.

"Calm yourself Kamado, look - look," Giyu urged as he pushed her back under the shade.

Nezuko wasn't sure what she was supposed to be looking at - the horror as her brother and Muzan burned away before her!?

Except...

Oh.

Tanjiro stood firm as he pinned Muzan down, his skin curling under the rays of the sun, but not burning to the extent Muzan's was. Muzan was writhing as his skin turned the ugly color of charcoal but Tanjiro's skin was nothing other than a bit darkened.

"You - YOU!" Muzan's accusing voice was hoarse and something akin to a scream. "HOW LONG - HOW LONG HAS THIS BEEN!? THE SUN DOESN'T KILL YOU!"

"This never could've been with you in my head," Tanjiro snarled. "You're a disease Muzan and there was never any way the sun wouldn't try to kill you. Any other demon free from you likely can - me, Nezuko... the other renegade demons you hunt. Never you... never you," Tanjro shook in rage as he kept Muzan still, the sun's full rays slamming into the two of them.

"CURSE YOU BOY! CURSE YOU TO HELL! DAMN YOU! YOU'LL NEVER BE FREE OF ME! DAMN YOU DAMN YOU - " Muzan cursed as his body dissolved into ash. He writhed and screamed like a child throwing a tantrum until the sun burned everything away leaving him nothing but a stain in the floor. 

Nezuko and Tanjiro felt something in their body seize as all of Muzan's cells infecting their body seized and threatened to tear them apart as he died - but something stalled it. Something within them burned like the sun and their demonic cells remained strong and vibrant as Muzan's invasive ones withered away.

They would not join the Demon Lord in his fate.

Tanjiro stood up, faltering slightly as his skin began to burn like little embers under the sun.

"TANJRIO!" Nezuko cried desperately, ducking under Giyu's arms and risking the sun again to drag her brother into the shade where he could be safe.

They panted there for a while, slowing their breathing and letting their skin heal before slowly glancing back at the stain in the earth where Muzan had lay.

"Did we... did we do it?" Kanao asked uncertainly. "Is he dead?"

Gyomei collapsed to his knees and let out a long, wonderful sigh.  "Yes... he is gone."

There was no celebration or whoops, only a collection of disbelieving looks and the collapse of a handful of exhausted demon slayers. They lay there, covered in wounds and bruises - a strange sense of peace on all of them.

"NEZUKOOOOOOO!" Nenitsu cried as he and Inosuke charged forward and basically tackled Nezuko in a hug.

"That was stupid Nebukon! Stupid! Stupid! Stupid!" Inosuke scolded as he knocked her on the head.

"Sorry," Nezuko laughed - but she wasn't really.

"That was so scary! My love you cannot put yourself in such danger!" Zenitsu sobbed.

"Love!" Tanjiro's childish outrage would've made Nezuko laugh if she wasn't full of such relief. She watched it like it was some fever dream as Tanjiro glared at Zenitsu. She laughed and threw herself into his arms, wrapping her arms around him and sobbing gratefully as she held him close. He gingerly returned the hug and they knelt there for a while, simply hugging each other.

"You're back... you're back, you're okay... you're back," Nezuko sobbed.

Tanjiro was crying too, his entire body shaking as he buried his face in her shoulder. "I'm home... thank you.... thank you."

The two demons knelt there, hidden from the sun's gaze and tearfully reuniting as the members of the butterfly estate rushed around and began tending to everyone's wounds.

They had lived... they had won!

But Nezuko couldn't care less, she had her brother in her arms... and that's all that mattered. As far as she was concerned, she'd never let him go again.

(One week late - shhhhh, you saw nothing~

But anyway, Ta-daaa, happy ending. I was tempted to write more angst and was gonna kill them both off - but then I thought "Immortal family trope" with Nezuko, Tanjiro, Tamayo, and Yushiro, and my mind went "HELL YEAH!" so that's what the epilogue will be about. I hope you guys like it - thanks so much for reading!!)