When Terry McGinnis went to the synthoid factory to purchase new synthoids for his training, he brought his friend Howard along. While Terry filled out the forms, Howard explored the plant, meeting Louie, who was illegally creating synthoids that could pass as humans for customers. The opportunity was too good for Howard to pass up as it would give him something he wanted; a girlfriend. Desperate for a girlfriend to gain popularity, Howard requested a red-headed synthoid completely devoted to him; using his parent's credit card to pay for it.
The next day, the synthoid arrived at Hamilton Hill High School, earning the attention of many colleagues. Nelson Nash tried to hit on her but she told him she was only interested in Howard. When asked her name, Howard named her Cynthia. But Cynthia overheard Nelson's plan to "put [Howard] in his place". Cynthia pushed a row full of lockers which headed towards Nelson like a bunch of dominoes, nearly killing him. When Howard's friends began talking about it, Cynthia responded coldly and said that Nelson wasn't a nice guy.
As he planned Howard's popularity began rising, so much that Chelsea Cunningham began flirting with him. However, Cynthia became over-possessive of Howard and prepared to drop a sign on Chelsea in order to have Howard for herself. Her plan had been foiled when Terry came to question her.
Later at Howard's party, Howard grew angry with the fact that Cynthia pushed and shoved anyone who showed the slightest interest in him. He decided to talk to Cynthia in his room (while everyone thought she was making sexual advances towards him). He tried to let her down easy, but she malfunctions and went crazy. Batman arrived and tried to stop her but she proved to be too strong. Howard tried to appeal to her, promising they can be friends; making Batman cringe in disbelief at Howard's naiveté in dating. At the last word, Cynthia overloaded, then exploded, destroying Howard's house. Soon after this, Howard's parents returned home to a demolished house and demanded an explanation for the damaged house and overdrawn credit card, accusing him for buying dynamite.
Although not designed as a battle synthiod, Cynthia possessed superhuman strength that surpassed even Batman's enhanced strength. She also possessed superhuman agility as she was able to twist her joints in ways that were impossible for humans.