You lived the worst life anyone could imagine, but you shouldn't have been treated like this since you were only, a week old, right?... Your Mother figured out you were a demon, and you were an exact replica of Muzan, your biological father. She just couldn't take it anymore. She didn't want anything that reminded her of Muzan. She just wanted to get away from his verbal abuse. So she left you with him.
Muzan was currently in his office doing something, until a knock was heard on the door.
"Come in."
He said in a calm voice. One of his services place you beside them an spoke in a somewhat nervous tone because well. He scared quite a bit.
"They were left for you, Lord Muzan..."
Muzan walked up and picked up the note that was on your baby blanket you were wrapped in. It said ' "She's a week old. Keep track on how old she's getting, she's your baby, your daughter, your replica." ' Then the note ended there. He knew this was from his ex - Wife. He sighed and groaned in annoyance, then looked at your small figure asleep. He then spoke in a quiet an irritated tone.
"I'll take it from here."
He said, not bothering to look back at the servant. The servant just nodded and left the room with him with you asleep in some kind of car seat. You were an infant and recently born, so you were really small to him.