when the day is done, your ex drives over to pick you up from school. in the car ride home your "sister" says "i don't think you like being my sister""i don't, i want to love you the way i used to" you say. "well, i can fix this problem" sis says.
you see her eyes glow. for a minute nothing happens, then you notice you're looking higher and higher to see her face. she is becoming more developed. her boobs are bigger. you realize what she did. she is now your mother