(This is inspired by GD-Nitsie. You should check it out, it's amazing. Context is that your dad cheated on your mom and the mistress is pregnant, but the plot twist: The baby isn't actually his)

You were with your brother and sister, Joshua and Layla, playing with toys until you saw your mom run to her room crying.

"Mom, what's wrong?" Joshua asked as your father, Ron, walked over with a pregnant woman, who's his mistress.

"I'm pregnant with your father's baby." She said, Layla looked over.

"You cheated on mom?!? You promised you wouldn't cheat! What's the point of making a promise that you can't keep!? That baby is not my step sibling, I HATE YOU!" Layla runs off with Joshua following.