Ariel is the daughter of Alan Fagan (the fourth Mr. Fear). Fagan used her mother, Cora Tremmore, for carnal pleasure and left, refusing to help care or take any responsibility for Ariel. As a result, Cora taught Ariel to hate her father and to strive to be better than him. After Cora was the victim of a horrific workplace accident, Ariel dedicated herself to her goal of being better than her father. As it proved to be an expensive undertaking, Ariel utilized a variety of ways of earning money, including theft and prostitution.
Eventually, Ariel paid a group of inmates to attack her imprisoned father and slash off a piece of his face. After receiving the skin sample, Ariel brought it to a chemist to examine it as well as produce a new, improved fear chemical. Ariel used this to transform herself in Shock, Mistress of Fear.
Using her newfound powers, Shock terrorized the population of New York and attracted the attention of Daredevil, who used his keen senses to track the scent of the chemical to Ariel. Transforming into Shock, she used her abilities to cause Daredevil to become enraged and then tackled him off the top of the building they were on. Both made it safely to the ground, but Shock escaped by using her powers to cause panic in the streets.
Shock then visited her father in the hospital. He was dying, but Shock tormented him until his vital signs began to strengthen. Daredevil tracked her down again and this time she caused him to hallucinate that he was being attacked by Elektra. Daredevil managed to keep clear headed enough to force Shock to consume another dose of her chemical, transforming her back to her human form. This made it far easier to arrest her, but while she was handcuffed, Ariel's hands turned back to their taloned form and she readied herself to break free.
By consuming the chemical synthesized by her father's skin Ariel transforms to a monstrous form with razor sharp talons. Shock can generate terror, rage and even hatred in others. Unlike her predecessors, she is capable of generating more than primal fear - she can also cause her victims to hallucinate their greatest fears.
She did not appear to be able to generate her emotion manipulating pheromones in her human form. However, the ending of her last appearance suggests that she may be able to transform to and from her monstrous form at will, rather than being reliant upon chemicals.