Author's Note: Hiii its me again! I'm back after a while with a new story! This one's based Demon Slayer Kimetsu No Yaiba. I recently got into the series and I fell in love with it. But I noticed there were NO sickfics of it on here. So to my disappointment I thought, okay time to take matters into my own hands here! And after a few months of thinking, I got this interesting idea. And I'm aware that the manga confirms that demons can't get sick, but hey Nezuko's a unique demon so maybe she's an exception) It'll be a bit more intense than my usual fluffy fics, this one has a bit of a story arc to it. As usual I hope you enjoy and I hope I do these characters justice or get their personalities right in the writing because I've only been into this series for a couple months.

This may also be my longest fic yet. I have some plans for this one c:

Chapter 6: Tanjiro finally finds a way to calm Nezuko down, with a little help from his mother.

Nezuko was still not comfortable despite her brother's efforts, and she began shivering and making various grunting and growling noises trying to move again, but the blanket kept her restrained. She was reacting badly again, just like before.

"Oh no, not again… I have to find a way to calm her down…" he said to himself looking down at her. "Think Tanjiro, think…!"

He dug deep in his memories to find anything from their family times, their childhood that would help settle his sister down. Was there anything their mother did to calm her down? Was there anything that brought her peace? Then he remembered a time Nezuko fell ill when she was a child. A human child. She ran a high fever, and he remembered their mother was tending to her. She was probably just a big as she was right now as a demon.

The memory played like a film in his mind. He could hear the voices. The images of his departed mother holding a younger Nezuko close to her in her house beside her futon. It all came back to him as he could hear the voices play in his head.

"Mommy… I feel hot… I'm scared…" a young short haired Nezuko said clinging to their mother out of fear.

"It's okay sweetie, I'm right here." Their mother said.

Nezuko clung to her mother, big wet tears in her eyes.

"It hurts…make it go away…" she said in between sobs.

Their mother stroked her head to soothe her "Being sick is scary, but once it runs its course, you'll heal. Here. Let me sing you the lullaby I always sung to you when you were a baby… Maybe it'll help you feel better."

"That's it! The lullaby!" Tanjiro said snapping back to reality.

He remembered his mother sung that song to Nezuko when she was little all the time. After she enjoyed hearing it when she was ill, it became her favorite thing. The one thing that brought her comfort, happiness, and peace. He remembered that she always asked their mother to sing it, even when she was feeling completely fine. The song just made her happy. But would it work when she was a demon with little to no memory of the past she lived as a human?

Tanjiro had no other option and Nezuko's flailing was getting more desperate, so he gave it a try. He tried to remember the words their mother sang to her. And along with the memory playing in his head as he closed his eyes, he begun to sing the song right alongside his mother in his head. The song became clear as he recalled it.

"Knock Knock, little bunny from the little mountain…"

He began. Nezuko continued to flail angrily, but he remained still as he concentrated.

"…Why are your ears so long?"

He could see his mother sing along with him in his head.

"When she was small. My mother, ate the leaves from a tall tree…"

Tanjiro kept going, making his voice as sound and calm as his mothers.

"…And that is why my ears are so long…"

As the lines went by, Nezuko's tantrum in the blanket came to a stop.

She was starting to settle down.

It was working and Tanjiro continued to sing the lullaby hoping it would put her to sleep.

"Knock Knock. Little bunny from the little mountain…"

He sang, as he saw his mother singing to the other nezuko in his mind. And she was starting to settle down too falling asleep on their mother's lap.

"…Why are your eyes so red?"

Nezuko made small, muffled noises as she settled down in Tanjiro's arms.

"When she was little, my mother, ate the fruit off a red tree…"

The other Nezuko sighed in their mother's lap soothed by the sound of their mother's soft voice.

"…And that is why my eyes are so red…"

Tanjiro continued the song until it eventually ended.

He opened his eyes looking down at Nezuko. And she was calm and sound asleep.

"Nezuko…" her brother said quietly. "Thank goodness…"

He put his hand to her cheek and noticed something. There were tears in Nezuko's eyes. And her temperature went down a little, but it was still high. But the lullaby soothed her enough for the panicked spike of her fever to go away.

Tanjiro hugged Nezuko's body close to him as tears came out of his own eyes. He was so relieved that worked and it was looking like Nezuko was going to be alright for tonight. He looked up at the moon in the sky and smiled.

"Thank you…Mother."

Tanjiro looked up at the sky and noticed it would be dawn soon.

He then got up slowly taking Nezuko back inside the inn. He decided for the remainder of the night he would move his futon to another room so it would be quiet so Nezuko could sleep peacefully, and he could rest beside her. He hoped she could sleep a little bit to regain her energy even if it were weak at the moment, and without proper sleep Nezuko wouldn't be able to sustain her replacement for hunger.

He quietly moved his futon to another room and set Nezuko down on it before going back to the original room and grabbed Nezuko's box and brought it with him to the room. He saw Nezuko begin to fuss a bit, possibly upset that he had left her. Tanjiro then gently picked up his sister with one hand and got under the blanket of the futon and sung the same lullaby to her again until she calmed down and fell back to a more peaceful sleep.

Tanjiro covered Nezuko's entire body with the blanket of his futon to shield her from any possible sunlight the morning would shine, even though he tried to place the futon in the corner where the sun wouldn't hit them. He figured she didn't want to be alone in the box and wanted to stay close to her brother for the time being.

Tanjiro smiled looking at Nezuko stroking her head reassuring her that he was still with her. He could feel her deep breathing on his cheek. She was still not in good shape, but he was relieved she had peacefully fallen asleep.

"Goodnight Nezuko. Don't worry, you're going to be alright…I promise..."

Tanjiro then laid his head down on the pillow and rested his eyes for the remainder of the night. Still holding Nezuko close to him.

Chapter 6 done! That's all I've written for now but I assure you I will be updating this soon!