AN: An idea where something happens to Tanjiro and he regains the humanity he lost, but loses the memories of him being a demon and doesn't know what's going on. The initial reaction to him realizing he wants to take a bite out of his sister. So since I had to put this at some point in the story line it would be right at the tail end of Mugen train. I figure maybe Akaza punches a fist through Tanjiro's entire skull and when he heals back the old memories just unlock.

"-and why do you still have your sword out?"

Nezuko's voice brought Tanjiro back to awareness. And with awareness came pain . The most intense pain that he had ever felt, that stole his breath and left him unable to do anything. He couldn't cry out, couldn't even open his eyes and even the tears that came up as an automatic response hurt. His head pounded with each heartbeat, so intense that Tanjiro wished for unconsciousness to escape it.

"You know why, Kamado-chan."

The unknown voice was a welcome distraction. Male and deep and loud, jolting enough that Tanjiro was able to focus on it for a split second despite the pain. Who was it? The doctor? Given the amount of pain he was in it was no surprise that his mom or Nezuko had sent for the village doctor, Tadashi. But the deep voice didn't sound like Tadashi's.

"He's awake already," a new male voice interrupted. "I can tell from his heartbeat."

The pain ebbed enough that Tanjiro could open his eyes and he looked at the bright blue sky overhead, white fluffy clouds spotted across the wide expanse here and there. He was in the shade somehow, but when he tried to tilt his head back to see what was casting the shadow he couldn't get it to move. He realized he couldn't move anything except his eyes and his eyelids and he darted his gaze this way and that in panic as he tried to figure out what was wrong.

"Tanjiro!" Nezuko appeared in his line of sight, "Thank the Gods, I was so worried!"

Nezuko was a welcome figure, but the sight of her still surprised him. Her favorite kimono, the pink one with the asanoha pattern that he had loved on her so much, had been turned into a knee length haori. She wore it over a black gakuran jacket that was completely buttoned up along with black hakama pants. He glanced down and saw that she had on a pair of black kyahan run through with a pink asanoha pattern that covered white tabi socks and a pair of pink laced zori. The hilt of a sword poked out of one side of the haori as she moved closer and he realized she had on a pair of hanafuda earrings exactly like his own. The only thing that seemed the same was her hair.

He had never seen her in pants before. This startling thought was quickly followed by another one–where did she get all these new things? The haori was her old kimono, but the rest of the outfit was something he had never seen before.

Nezuko knelt next to him and to his relief he found that he was able to turn his head towards her.

"N-" Tanjiro had to swallow against a dry throat, "Nez…zuko…"

Nezuko's eyes widened and her mouth fell open. Another figure appeared beside her, a boy with blond hair that ended in orange tips and a uniform that was similar to Nezuko's, and he fell to his knees with a grin.

"He can talk!" This blond was the second voice that had talked, "Look at that! That's great, Nezuko-chan!"

"Water…" Tanjiro requested weakly.

The surprised look on Nezuko's face changed to one that he couldn't read, and the grin dropped off of the blond's face. They exchanged a look and Tanjiro tried to inhale to get an idea as to what was going on but he couldn't smell a single thing for some reason. Outside of being able to move his head some, nothing else seemed to respond with anything but very minimal movement. He gave an experimental wiggle of his fingers but his toes refused to budge. Tanjiro coughed and swallowed a few times to try and wet his throat with what little saliva he could work up, confused as to why Nezuko wouldn't offer him any water. Doctor's orders?

"What happened?" Tanjiro croaked, "What's wrong with me?" And then another thought hit him, "Is mom with the doctor, or is someone else sick?"

Tanjiro had never had an illness or injury where his mom wasn't right next to him, holding his hand or wetting his forehead with a cool cloth. The only way she wouldn't be near him now was if she was talking to someone else or one of the other kids was sick.

"Tanjiro…" Nezuko's brow furrowed, "Tanjiro, what are you saying?"

"He took a hard blow to the head, my girl!" The loud, deep voice was back and Tanjiro turned his head away from Nezuko to see a man with shoulder length blond hair tipped in red. Between his hair, his eyes, and the haori, he reminded Tanjiro of a flame. "Perhaps his memories took a blow, too! Could even be scrambled, I dare say!"

Missing memories would certainly explain a lot of things. These strangers recognized him but he had no idea who they were, Nezuko's change of clothes, why the rest of their family wasn't anywhere to be seen, why he couldn't actually remember getting sick or injured to explain why he felt so much pain, and the different season given the leaves on all the trees.

"What's the last thing you remember?" Nezuko leaned forward, eager for his answer.

Tanjiro thought back, "You went to the village to sell charcoal for me because I had a cold. I remember my fever broke so I tried to stay awake to wait for you because I was certain you'd be stubborn and try to return that night even with all the snow, but… I must have fallen asleep at some point. I don't remember anything else."

Nezuko closed her eyes for a long moment and for the first time Tanjiro felt a small inkling of dread fill him. The blond beside her reached over and put a hand on her arm and when Nezuko opened her eyes Tanjiro could see that they were filled with tears. She stood up, brushing the blond's touch off as she stepped back away from them both. Now that he looked again he was sure she was taller.

"Everything," Nezuko moaned. "Everything!"

"Nezuko, it's okay!" The blond jumped to his feet, "I can explain things, if you want!"

Nezuko shook her head, "How is it that I've lost him twice and he's not even dead, Zenitsu?"

Her voice was thick with tears, and Zenitsu pulled her into a hug. Tanjiro watched and tried hard to remember who this Zenitsu was but he couldn't recall a single thing. They obviously had to know him well if he could hug Nezuko so easily and she in turn could lean on him for comfort, but to Tanjiro he was nothing more than a stranger.

He tried not to think too hard about Nezuko's words, but he couldn't stop himself. Lost him twice? Was this the second time now that he had lost his memories? How much time had passed since what he last remembered?

Where was the rest of their family?

"Things seem alright for now, but you should both stay aware." Tanjiro turned his head to see that the man of flames was staring directly at his sister and Zenitsu, "I'm going to go see if any others need assistance, but if he should start to-"

"I know," Nezuko pulled away from Zenitsu and Tanjiro was surprised to see her glare at the man. "I know , okay? I won't let him, Rengoku-san."

"Alright," Rengoku made his tone gentler, "My apologies."

And then he left, and Tanjiro was stuck in the same position as before. At least a lot of the pain had faded.

"I can't move much," Tanjiro said, because he wasn't sure what else he should be saying.

Sorry? What's happening? How did he get here? Nezuko was aware of all of those questions, now. He could see every one of them weighing down her shoulders, telling him that he wouldn't like the answers.

"That's…" Nezuko sniffled and took a deep breath, "That's probably because of the blow to your head. Here, let me…"

Nezuko knelt next to him again and the next thing he knew she was putting a hand just under each shoulder and lifting him half up so she could slide his head onto her lap. It helped relieve the ache some more, and all at once his nose seemed to work again. The most delicious scent he'd ever smelled assaulted him, making his mouth water.

"I'm hungry," Tanjiro realized.

The hunger was so intense and the gnawing pain so great that he had assumed it to be just something else among the many pains racking his body. He inhaled deeply, trying to figure out what the mouth watering scent was, and he turned his head towards Nezuko as he realized it was coming from her. There was something staining the front of her uniform, some kind of liquid that smelled heavenly.

Saliva filled his mouth and he had to swallow past it as he focused in on the source. Red and filled with life, with energy, and it was right there, so close, he just had to lean forward a little and bite, just had to sink his teeth in and teartearripconsumesohungrysoemptyeateateat–

"Tanjiro."

Nezuko's voice brought him back and all at once he realized he was staring at a rip in her uniform, the skin shining red with blood that sluggishly leaked out of a small hole in her stomach when she breathed. The scent was still alluring and his mouth was still watering, but his mind screamed at him because this was Nezuko! He was looking at Nezuko like she was some kind of delicious snack, and his stomach turned at the thought of hurting her. He tried to push away from her, but Nezuko held on tight.

"Let me go!" Tanjiro demanded, disgusted and horrified with himself. "I don't want to hurt you!"

"It's okay," Nezuko soothed, but she wasn't looking down at him. "Just… Just go back to sleep, okay? It'll be better when you wake up, I promise."

Tanjiro wanted to argue more, but something hit the back of his neck and everything went dark.