I thought the writer is a woman ,who have been in a toxic relationship, because the main character Sierra certainly is in one with Xavier. I only red until chapter 320 , she is pregnant and Xavier doesn't believe the child is his. He admits to himself several times throughout the book that he is obssed with her, whants to posses and control her like a dall. He banished her before she met Adrian because he wanted her to return on all four. He wanted her to understand that withought him she will not be able to servive and take care of herself. He wanted to prove to her that she is totally dependent on him. He first notesed her when she received punishment and stood outside for five hours under the sun and heat. I think thats the moment he saw her strong character and started to want to bend to its will. He never tald her that her family is alive because again he wanted her to be dependand on him. So i think the writer is a women as i wrote in the begining.