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Nightmares after missions had become a normal thing for Tanjirou.
Usually, looking over to see Nezuko's sleeping form was enough to settle him, knowing she was safe and they'd both lived to see another day. That there was still, however small, a chance to move forward and turn her back into a human so she could live a normal life again.
But Nezuko was absent from her bed. Though he knew the Butterfly Estate was a safe place for them, and he had no reason to truly worry, the instinct to do so was so deep in his body that he was immediately wide awake and sitting up in place, looking around.
She wasn't in her box either, so he left their room to go search for her. No one was awake, it seemed, with all of the lanterns out and the rooms he passed by were silent besides a snore here and there. His mind whirled with possibilities of where Nezuko might have gone.
Down a hallway closer to the back of the estate, Tanjirou heard laughter.
It wasn't loud, considering the hour of the night and mostly everybody inside was sleeping, but it was quiet enough around him that the sound reached him anyway.
Another quiet laugh brought a smile to his face, instantly relaxing. He knew the sound well, after months of hearing it on and off when he was at the Butterfly Estate. (Y/N) was awake. Surely she would have seen Nezuko somewhere.
Tanjirou came to a stop at the end of the hallway by an open door, the cool breeze hitting his face. Outside, (Y/N) was kneeling in the grass, faced away from him, looking down at something in her hands.
"Look," she said, soft glee in her voice. "Isn't it pretty?"
He leaned against the wall, looking at her fondly. She giggled. "Hold on! Be patient, it will light up again in just a second. See!"
A firefly flew up out of her hands, and Tanjirou saw it soar up into the night. (Y/N) stood up, back still turned to him. "You ready to try catching one yourself?"
A little "Hm!" startled him, and his heart clenched with relief. (Y/N) stepped to the side, and Tanjirou watched as Nezuko in her smaller form ran around (Y/N)'s legs, hands stretched upward. "Mm?"
"No, no, not like that," (Y/N) said, crouching down. "Here, let me help you."
Nezuko frowned, reaching one hand back up with her palm facing flat toward the ground.
"Yes, I know you could grow big and tall to reach them," (Y/N) smiled, so soft and patient with Nezuko that it brought tears to Tanjirou's eyes. "But you have to save all that energy so you can save the world with Tanjirou-kun, yeah? Come here."
(Y/N) held out her arms, and Nezuko toddled over and let herself be picked up. "Mm."
"Okay, Nezuko. Reach out real slow, cup your hands together. Yeah, like that! Now we have to wait for one to come close, and then you have to be really careful when you close your hands. You don't want it to get out, but we wanna let it go after, too."
"Mhm."
Tanjirou saw the stars in his little sister's eyes, and the warm look on (Y/N)'s face, and a tear rolled down his cheek. Nezuko's face lit up in absolute glee when she finally caught a firefly, and turned to (Y/N) looking so proud of herself.
"Good job, Nezuko!" (Y/N) cheered. "See! You're a natural!"
"Hm!"
Nezuko made a sad noise when the firefly flew out of her palm, but she looked back to (Y/N), still smiling so softly at her, and she threw her small arms around (Y/N)'s neck for a hug.
(Y/N) hugged her back tight, spinning in circles with a happy laugh.
Tanjirou thought back on the last few years, on every person he'd introduced Nezuko to, and how she was always met at first with distrust and hostility. Even those who had come to trust her and care for her still sometimes got a little on edge, besides a few select people. To see (Y/N) treating his little sister with such love and care had his heart pounding hard in his chest with so many emotions.
It was almost overwhelming.
Nezuko shimmied down out of (Y/N)'s hold, and she watched his sister run off to the other side of the garden with a patient, gentle grin on her face. The moonlight made her look like she was glowing, almost. Her butterfly hairpins shimmered, her eyes glittered. She was beautiful.
Of course, he'd known this already, but he was so blessed to have woken up and seen this moment between her and Nezuko.
His put a hand over his heart, feeling it beat stronger under his palm.
Oh. I love her.
She suddenly kneeled back down to the ground, smoothing her kimono over her lap, and her smile widened. Nezuko ran back over to (Y/N), stopping right in front of her. His sister held out a handful of flowers, shaking her fist to get (Y/N) to take them.
"For me?" (Y/N) softened.
Nezuko nodded. "Mm."
(Y/N) took the flowers, and picked one out of the bunch. "Thank you, Nezuko. They're beautiful."
The one she took out was twirled between her fingers, and she brought her hand up to her head, removing two of her butterfly clips and moving closer to Nezuko. She clipped the flower into Nezuko's hair, tapping it once to make sure it was secure in place, and patting the top of Nezuko's head. "There. Now you have one, too."
Nezuko smiled, eyes closing and cheeks lifting around her muzzle. "Hmmm!"
(Y/N) leaned forward and cupped her hand around Nezuko's ear, whispering something, and Nezuko straightened with a nod. (Y/N) picked another flower out of the bunch she'd been given and handed it to Nezuko with the other clip, and Nezuko turned, running straight to Tanjirou.
He straightened in surprise, having thought he'd been quiet enough for them not to notice him there, but (Y/N) always had been more observant than anyone gave her credit for. He caught Nezuko and lifted her up to sit on his hip, and saw (Y/N) out of the corner of his eye giving him a smile and a wink, wiggling her bundle of flowers at him and nodding to Nezuko.
Tanjirou smiled at Nezuko. "Hi, Nezuko. Are you having fun with (Y/N)?"
Nezuko nodded, smiling, and reached up with her empty hand to pat the top of Tanjirou's head, gently tugging down on his hair. "Huh? Oh, you want me to tilt my head down?"
"Mm."
Her little fingers slid through his hair up by his scar, and he felt (Y/N)'s butterfly clip latch in place. Nezuko patted his head again, and he looked back up to her, teasingly looking up to try and "see" his head. "Just for me? Wow, thank you!"
Nezuko pointed behind her at (Y/N) and made grabby fingers, so Tanjirou walked over to her.
(Y/N) looked at the flower in his hair and gave him a playful smirk. His chest tightened, a blush rising to his cheeks. "Pretty flower. It's perfect."
She patted Nezuko's head once more. "Goodnight, Nezuko," her smirk softened, and the smile she gave Tanjirou melted his heart. "Goodnight, Tanjirou. See you tomorrow."
Then she walked inside, turning in for the night, and Nezuko giggled behind her muzzle. Tanjirou turned to her. "What is it, Nezuko?"
His sister pointed at the flower, eyes bright, and then pointed at his chest, then where (Y/N) had gone through the door. She clapped her hands and nodded.
Tanjirou shifted his hold on Nezuko, holding her with one arm under her legs, and unclipped the flower with the other hand.
He stared down at the blue forget-me-not in his palm. Nezuko giggled again, making a happy noise, and Tanjirou turned to look down the empty hallway (Y/N) had disappeared down.
The flower's petals ruffled in the breeze, and he curled the tips of his fingers around the stem so it wouldn't blow away. (Y/N) had specifically picked out this flower from the bunch Nezuko had given her, and made a pointed comment about it before she'd gone inside. He grinned to himself.
A forget-me-not.
True love.