Half-Demon! Tanjiro AU

Chapter Four: Happy Birthday!

Warnings: A small bit of angst.

Word Count: 3158

  "So, we're just going to keep a demon here?!" Zenitsu practically squealed to Tanjiro. The Kamados decided that the best place for Rui, or at least the best place for him at this moment, would be at the Butterfly Estate. It was a cozy and comfortable environment. Perfect for a demon trying to adjust to a new life. Tanjiro also figured that the girls wouldn't mind him, since Rui is a child.
  And to an extent, Tanjiro was right. Aoi was a bit nervous, not even really speaking to Rui when they introduced him. However, Sumi, Kiyo, and Naho adored him. They smothered the small demon with affection, which both confused and warmed him. Zenitsu and Inosuke were obviously rather surprised when Tanjiro brought the small demon home.
  "It's okay, Zenitsu. They performed the blood test on him. He's okay." Tanjiro crouched down next to Rui, who was covering his ears and wincing like a hurt puppy. "Oh yeah? What if he's just faking?! He'll kill us in our sleep!" Zenitsu's voice was filled with confusion and fear. Rui only winced even more. "Please stop yelling.."
  "Is he a training dummy?" Inosuke snorted with his raspy voice. "No. He's not a punching bag nor is he going to kill us. Please just listen to him." Tanjiro spoke softly as to not agitate the small details further. Nezuko put her hands over Rui's to soothe his senses. The Kamado siblings knew that all this change was a lot for anyone to handle.
  After a few seconds of silence, Rui looked at Nezuko, who nodded reassuringly. He took a deep breath and looked at Zenitsu and Inosuke. "I'm not going to hurt anyone here. I know that it's hard to believe me, but I'm telling the truth." Rui spoke with a shaky, yet soft voice.
  Zenitsu closed his eyes and listened to the small demon's sound. Rui's body rhythm sounded strange. It wasn't like a demon's or a human's. It was..a combination of both? Growls and purrs could be heard from inside him, but they were much more soft and gentle. Zenitsu was surprised by the demon's sound, so he kept his composure. "Fine..fine..but you're keeping an eye on him."
  Tanjiro smiled and sighed in relief. "Don't worry, Zenitsu. Everything will be okay, right Rui?" The young demon rumbled sheepishly. "Right." Everything felt incredibly overwhelming to Rui. He was terrified that the slayers' prejudices would lead them to kill him at any opportunity they might get.
  Tanjiro squeezed his hand lightly, reassuring the small demon. Rui looked up at the much larger demon, who tilted his head and smiled. Closing his eyes and taking a deep breath, Rui stepped forward with the Kamado siblings and headed further into the Butterfly Estate.
  Everything felt so foreign, yet so familiar-like an old children's book being dusted off after years of neglect. The white walls were blinding to the young demon. Such brilliant light was striking, especially since Rui hasn't seen this kind of light in decades. In a way, he missed this beauty. It vaguely reminded him of what he missed when he was human.
  "Here. This room hasn't been taken by any guests." Aoi huffed coldly. Both Rui and Tanjiro felt a sharp chill crawl up their spine, thus making the small demon wince. "Thank you, Aoi." Tanjiro gave her a small smile as both he and Nezuko led Rui inside.
  The room wasn't too different from the others. A neatly made futon rested in the back-center of the room. A small desk sat on the right side while a bookshelf covered the left. Two warm lamps were hung on the walls above the futon. Thus providing the room with light and fire, along with the window of course.
  Rui took a few steps into the room, scanning the scene. "I know it isn't much." Nezuko said softly. "But we hope you like it." Rui looked around for a few more seconds, being particularly mesmerized by the lamps. "It's cozy..I like it." He turned to the others with a warm smile. "Thank you."
  "Of course, Rui. Make yourself at home." Tanjiro beamed with happiness, glad that the demon liked his new living space. "I know that this is a lot of change, but we'll help you get used to it." Rui hummed as he heard Tanjiro speak, pleased and warm.
  "Caw! Caw!" A sharp screech broke the tender moment. Matsuemon came swooping in through the bedroom window, carrying a letter in his talons. "A letter for Tanjiro! A letter for Tanjiro! Caw!" The crow continued to screech, flying in circles above them.
  Rui squeaked with surprise when the crow flew in, while Tanjiro smiled at the bird. "Ah! Thank you, Matsuemon! Who is it from?" The crow cawed and landed on his shoulder. "See for yourself!" Tanjiro gently took the letter from his crow. Nezuko and Zenitsu tried to look over his shoulders while Inosuke climbed his back and peered over his head.
  The letter read as follows, "Dear, Tanjiro, I just heard of what happened at the Infinity Castle and your transformation. I hope you're doing okay, since dealing with the changes and the opinions of the other slayers must be incredibly difficult to deal with. I haven't told father yet because I don't want him to cut off communication between us. Please let me know how everything is going as soon as possible. I'm just really worried about you. Sincerely, Senjuro Rengoku."
  Tanjiro smiled warmly at the thought of the young boy. "Senjuro's just too sweet." He hummed softly. Rui tilted his head in confusion. "Senjuro? Who's that?" Nezuko looked up at Rui. "Oh, he's an old friend of ours. Senjuro is the brother of one of our best mentors."
  The very thought of the Flame Hashira brought sadness to them all. "But he's gone now.." Zenitsu's voice was soft and sorrowful. Rui could tell that whoever this person was, he clearly meant a lot to them. "I'm so sorry..He must've had a deep bond with you." They all nodded. "He was one of the best." Tanjiro whispered.
  "Hey! Isn't it Dencuro's birthday tomorrow?" Inosuke perked up, lightening the mood. "I believe so!" Tanjiro's voice grew with excitement. "So you can remember his birthday, but not his name? You make no sense." Zenitsu scoffed, huffing in agitation. "Well, at least he remembers his birthday!" Nezuko purred with enthusiasm.
  "But he hasn't celebrated his birthday since..." Tanjiro rumbled softly. He wanted to celebrate the special occasion with Senjuro, but the young slayer knew that Senjuro wouldn't enjoy it. It just felt empty without Rengoku. The others seemed to feel the same, looking down with guilt.
  Rui put a hand to his chin, thinking. Then, an idea hit him. He wasn't sure if the others would like it though. "I have an idea." The small demon spoke up. The group turned their attention to him. "Sure, what is it?" Tanjiro sounded like he was trying to hold back tears.
  "Well..since you were able to bring me back by accident, maybe you can..." Rui's voice faded by the end. He really didn't know how the group of slayers would react. The squad all looked at each other. Some of them nodded slightly. "It's worth a shot, don't you think?" Inosuke's usually raspy voice sounded rather soft. They were actually considering the idea!
  Tanjiro looked at his claws, getting lost in his mind. He seemed to be the only one who can create these kinds of beings. "If it makes Senjuro happy,.." Tanjiro turned to the others with a determined smile. "Then it's worth a shot!" The group cheered with enthusiasm. Rui smiled to himself, glad that he was helping them.