In general, what is known as the Remnant causes the supernatural phenomena of the animatronics to get haunted and thus gain sentience. The Remnant is a metallic substance that binds living souls to all kinds of inanimate objects, forcing them to coexist with their new “body.” Therefore, from the outsider’s perspective, it appears as if the object is haunted. It is theorized from Circus Baby’s blueprint that her mechanical claw, or the scooper, was integrated with a piece of the Remnant. Thus, when Circus Baby grabbed Elizabeth with the scooper and proceeded to kill her, Elizabeth’s soul was bound to the animatronic. As such, Elizabeth began identifying herself as Circus Baby, having accepted the state of coexistence.