Shayle was born in the town of Zeza, a small village in Remnant controlled territory. Early in her life, she was always dreaming and wishing that she didn't live in the Wasteland, instead preferring to imagine she was in the Pre-War world. Using only what she learned from the stories of her parents and the villiage elders, a young Shayle practiced origami using scrap paper to create the flowers she heard about in these stories; her favorite thing that the Old World had.
Her life changed dramatically at the disappearance and assumed death of her mother while giving birth to Felix, and the filly would be forced into a life without the color she once sought to create. Following her mother's death, Shayle's father grew more and more strict as a parent, relying heavily on alcohol to deal with the loss of his love. Unfortunately for his children, this grew a new, more oppressive side to his personality. He would beat them on occasion after a night of drinking to forget, mostly focusing on the older of the children; Shayle. He even went as far as to forbid his daughter from attending school, relying on her to perform household chores and care for Felix while he was working or otherwise away.
After years of this abuse, the treatment reached a new level when the stallion raped a 12 year old Shayle in the night. Over the next 5 years, Shayle's life spiraled into nothing but misery as she became a puppet for her father, only finding comfort in the fact that her brother seemed to be spared entirely as long as she was around to be targeted. When she couldn't take any more of the abuse, Shayle found a way to end her misery while still sparing her brother.
The last night before the two siblings ran away, Shayle stabbed her father to death in the hallway; an act which she still holds secret, refusing to tell anyone for fear of the consequences.
A list of Shayles perks can be found here.