A week later...
Shinobu had just returned from patrol late in the night when she noticed the mansion was unusually silent.
'What happened??'
Instantly, she was alarmed and hurried, only to realize that it was quite late in the night and other Demon Slayers under her were asleep. Well, except for the ones on guard.
"Hashira."
They greeted her as she walked inside, returning to their duty a moment later.
'Why was I scared? Must be because of that demon.'
She had been expecting Douma to visit for quite a while now however, he hadn't shown up since. Did he know about their intentions?
Suddenly, the wind blew across the courtyard softly with a veiled chill in it, startling her.
Looking up, she saw someone standing on the fence in a relaxed manner while holding a pair of beautiful fans.
Douma.
Her body tensed.
"Otto, Otto..."
Douma cooed, his charming smile illuminated by the moonlight.
"I come in quiet peace tonight..."
He clarified, causing Shinobu to relax a bit.
"I can see you've been expecting me." His smile slowly receded. Rare—Shinobu noted.
"I was." She declared, masking her nervousness. "I was hoping I could strike a deal with you."
Reflexively, Douma smiled. "A deal with a demon...? So curious."
"I know you want something from me. In exchange for that, you'll help me build my poison against demons." She answered bluntly.
Douma was quite surprised, yet not. Shinobu was always straightforward. Well, cunning sometimes. However, what she said was quite true. Her poison was quite lackluster compared to her future self. Well, it wouldn't hurt helping her.
He took a single step—and appeared before her.
"I can smell rage, hesitation, confusion and determination from you. However, I don't care about those. What I need to know is how..." He paused. "Never mind. I'll find out myself."
He walked around her, suddenly smirking.
"Has Shinobu-chan grown taller?"
Shinobu felt herself go slightly red. What was he talking about?! Her height?! She knew she was quite short, but still—!
"Forget it! Come in."
She scowled, then walked inside dismissively.
Douma complied quite easily, having confirmed the absence of other Hashiras nearby.
"Your two guards aren't around?" He asked, referring to Obanai and Giyu.
"No. And they're not my guards." Shinobu answered coldly.
"If you say so..." He hummed, quietly following behind her.
Once they reached her laboratory, she turned to him.
"Let me iron this out. No touching of any human in my mansion. Understood?"
"Eto~ what if I'm hungry?"
Douma pouted.
"Then go die!"
Shinobu spat, sliding the door open while Douma sighed in disappointment.
Inside were several beakers and test tubes filled with chemicals and demon blood. It looked like a dark lab.
"Ah. I see. Shinobu-chan is so hardworking."
Douma praised genuinely.
Instead of answering, Shinobu shot him a cold look and pointed to a chair.
After ensuring that Douma was seated, she went to her finished experiments and took out five of her most potent poisons, injecting them into different syringes.
"Here we go."
She injected the first. Douma didn't even flinch, showing how useless the poison was.
She injected the second. His reaction?
"Ahahaha! It tickles."
She injected the third. His skin whitened briefly before normalizing.
Frustrated, she injected the fourth and fifth. Yet, no reaction.
Shinobu was disappointed. And seeing that... Douma smiled at her.
"Maa, Shinobu-chan shouldn't be disappointed. It's only I who has grown immune to wisteria among we demons."
Shinobu was stunned.
"Immune?"
She turned to him, alarmed.
"Well, it doesn't really hurts anymore. Just a bit ticklish." He explained.
Shinobu fell into deep thoughts. If Douma could grow immune to wisteria, could other demons also grow immune? That would make her power useless!
However, she wasn't going to give up easily.
"Let me take a sample of your blood."
She said, however, his hands suddenly grabbed the side of her face, intently staring into her eyes.
"Is that panic I see?"
He asked, his smile thin.
Shinobu tensed, then took a deep breath when she noticed how gently he held her.
As swiftly as he held, he removed his hands from her, seemingly understanding something.
"Continue."
Shinobu could only shake her head inwardly, wondering what kind of Demon he was.
...
Over the next few weeks, Douma visited Shinobu daily, helping her find chemicals that could hurt him while he explored the faint attachment he felt towards her.
During this period, he noticed that Shinobu had gotten quite used to his presence. Not being all-time-tensed whenever he was around and even frowning less.
Surprisingly, her experiments had been progressing speedily. Probably because she had an Upper Moon as a lab rat. Quite ironic... a demon working with a demon slayer?
At this point, even Douma had realized her talent. Despite not being physically strong, her poisons made her deadly. Even he was starting to feel a bit of pain. Just a bit, though.
Perhaps, this was the reason he admired her? He wondered emptily.
Tonight however, Shinobu chose to do something different. Something out of order.
"Sit."
Douma smiled softly, sensing the shift in her behavior, but happily complied. She couldn't kill him, anyway.
"Are we not treating your poisons tonight?" He asked coyly.
Shinobu forced herself to look calm, then spoke.
"Yes. Instead, I'll be asking you questions."
Douma nodded. Anything was fine.
"What do you want from me?" She asked, eyes shimmering with barely restrained emotions.
"What I want from you...?" Douma asked himself, seemingly unsure. "Hmm. Should I call it fascination? I simply enjoy your struggles and fierce determination."
He smiled.
"Combined with the hatred you harbor towards me for killing your sister."
Snap!
Shinobu's sword dug straight into his throat, while a calm smile remained plastered on his face as if he hadn't just been attacked.
"Hmmm. Your attack packs quite some strength."
He laughed softly, ignoring her trembling hands and furious expression.
"How dare you—!" She snapped, "Talk about my sister! Demon!"
She attacked furiously, almost destroying her own works, however, Douma easily restrained her—pulling her into a hug with her sword dug into his torso.
"This is what I fail to understand. Why are you so angry?" He whispered, feeling tears on his shoulders. "Isn't killing her good? She won't have to fight futile battles any longer. I have ate several Hashiras and I'm even starting to grow bored. The cycle is bland."
His smile dimmed.
"Everyone is just so sad..."