I Became the Villain’s Sister

Weren’t you supposed to bear me a son?
I became the protagonist’s sister, used and discarded by my family, destined to die.
I married the Emperor to save my youngest sibling, but the Emperor is acting strange?
“Ah, I never said I would bear one…”
“Really? Then, just follow my lead.”
“Um…?”
Approaching me languidly as if drunk on wine, he ran his hand through my hair.
“You will bear my son.”
“…….”
“Understood? Now, let’s head to the bedroom.”
What a terribly cliché and dull proposal, right?
But this man, he’s a bit dangerous.
And now, the youngest sibling and this man’s son too… My fake family is starting to obsess over me?