Hysteria is one of the few surviving members of the Bloodborne , and a frequent adversary of Lust.

Hysteria was one of the Shifted, born as part of an accelerated genesis program in an effort to quickly breed more soldiers to partake in the Blood Wars. Unfortunately, she was one of the many born with side effects.  She developped mild empathetic sensory powers that she had trouble controlling, which often caused her to have psychotic episodes with a diminished sense of self.

Soon after Hysteria was born, backlash against the accelerated programs began to spread. New evidence of both physical and mental defects in the offspring caused them to be viewed as subclass citizens, and they were used as effective scapegoats as to why the war was being lost. Her first living quarter was attacked by radicals in an effort to stem the accelerated programs, leaving her to fend for her self as an orphan before being rescued by Mania , an older boy from her same program.  They lived on the streets for several years before being taken in by Velleity .  Velleity brought them to a hidden sanctuary of those rejected by the Bloodborne, where they would remain into early adulthood.  Hysteria had difficulty understanding what had happened, but Mania was old enough to understand their circumstances, and grew resentful against those that had cast him out.  

One day a young Hysteria had a breakdown out of nowhere and ran outside of the shantytown in fear.  Mania was quick to go after her but only afterward realize that she was responding to sensations caused by a fleet of Bloodborne soldiers who were approaching.  They burnt the sanctuary to the ground and killed everyone in it. Mania hid the truth from her, and simply said they were leaving to find a new home. They left the country never looking back, and managed to escape the ramifications of the Blood Wars.

They would travel aimlessly, stealing what they needed and attacking those they felt deserved it. They quickly became adversaries of Cardinals for their survivalist attitude, especially Lust, a fellow Bloodborne. Mania despised her for having the life he never could, and Hysteria for the most part just went along with it.