In the seventeenth chapter, it's revealed that Layla isn't Madilyn's sister. Madilyn's real little sister, Tina, burned to death in a fire, along with their parents, while cerulean flames from Gaia that alter minds mixed Layla and Tina's memories to make Layla think she was Madilyn's little sister. Her parents had already planned on adopting Madilyn after the fire, and when Layla woke up after the incident with her memories altered, no one had the heart to tell her the truth, nor any idea how this happened or could be reversed. Furthermore, since Layla and Tina were practically mirrors of each other, Madilyn was terrified to let her know the truth out of fear that she might lose the only thing left of her sister. The writer was certain he'd get comments telling him that the readers hated him after pulling such a sad twist.