Betrothed to My Sister's Ex

Sorry for the delay, this turned into a trilogy... This is the middle part!

Life at the duke’s mansion was peaceful.

...There were quite a few who gossiped spitefully, saying I was the child of a concubine, but Lady Ryuu-Ryuu protected me. As promised, Duke Granado gave me opportunities to learn.

Still, I never thought of myself as their child—or a true member of this household. Since I was still young, I believed I was simply being cared for by kind adults. Naturally, once I grew up, I would stand on my own two feet.

So, I never sulked or acted out. However...

“Mio! You went outside again without permission...!”

Like a stray cat, Lady Ryuu-Ryuu grabbed me by the scruff of my neck and dangled me.

“I told you, a six-year-old girl can’t be out alone, it’s dangerous. How do you keep running away from home every single time? The mansion is surrounded by iron gates and there are gatekeepers, after all.”

Lady Ryuu-Ryuu and Duke Granado tilted their heads in confusion.

The secret was simple to reveal. I had secretly dug holes here and there in the garden to make underground tunnels, destroyed parts of the stone wall and hid the damage with wooden boards, jumped over gates by swinging on tree branches taller than the gates, copied the back gate’s key... using the wit and strength of a six-year-old, it was all quite ordinary.

And so, I often ran away from the Duke’s mansion to look for work.

Childish cunning? No. At that time, the royal capital’s economy was more unstable than now, children's rights were minimal, and child labor was rampant. Since I could read, write, and do arithmetic, there should have been some jobs for me at the market.

Thinking that, I walked to the market every time, only to be found by a messenger from the Granado Family.

Every time I was brought back, I was severely scolded. Lady Ryuu-Ryuu was always genuinely furious, sometimes even shedding tears—

“Don’t cause me so much worry...”

—while holding a young boy in her arms.

I was loved by both Lady Ryuu-Ryuu and the duke. They raised me as tenderly as if I were their own child.

Yet... precisely because of that, I felt that things couldn’t just stay as they were.

Their biological child was that boy. The two-year-old had a stern look just like the duke. His skin, hair, and vivid green eyes were the same color as Lady Ryuu-Ryuu’s.

I, with my dark brown hair and blue eyes, resembled neither of them. Of course.

I was not a child of this house—I had never considered it until that boy was born. But every time I looked at him, it felt like the truth hit me hard.

...Seeing that infant made me feel sick. I was scared and uneasy. I wanted to leave this mansion as soon as possible. Before being thrown out or hearing the words, “After all, blood relatives come first,” I wanted to escape.

Every single day, that was all I thought about.

Lady Ryuu-Ryuu never pressed me on why I ran away. Perhaps she sensed something, knowing words alone wouldn’t convince me.

There were signs that I would definitely complete my running away someday. Maybe next year.

But then, one day—

“Mio, I have a favor to ask. Could you please take on a job for me?”

Lady Ryuu-Ryuu said this, clasping her hands in front of her face and bowing to me. What was it? An errand? I nodded, still a six-year-old girl—only to realize what she pressed into my hands was her own son.

The two-year-old was standing upright with his arms and legs hanging loosely, sound asleep.

“...Huh?”

I blinked in confusion, looking back and forth between the boy and his mother. Lady Ryuu-Ryuu winked playfully at me.

“You’ll babysit Cyrus. Take care of him.”

“...Huh?”

“See, I still can’t speak the kingdom’s language very well, right? It would be bad if my son picked up my rough way of speaking. You speak more properly than me, so please talk to Cyrus a lot.”

“Eh... what? Huh!?”

“Honestly, I’m just tired of raising a kid! I finally weaned him, but he keeps following me around and is such a handful! Please, Mio-chan, help me babysit?”