Rebecca Gibson was a young woman who committed suicide after being abused by her father, Bill Gibson.
Rebecca's mother died giving birth to her, and twenty years later, Rebecca hanged herself. Both of them were cremated.
While investigating the family house, Sam and Dean Winchester discovered from Rebecca's diary that Bill had raped, impregnated and verbally abused his daughter, and kept their child locked away inside the house. Sam and Dean surmised that she broke out and killed Bill.
When Danny, the young son of the house's new owners disappeared, Dean went into the basement to rescue him and encountered a second child, a boy. After the boy attacked, Dean shot him. The girl found Susan and Kate Carter where they hiding and attacked them with a knife. Brian Carter killed her to protect them.