The man who would become Impasse once worked for Caesar Cicero. The crimeboss once got a drug charge dropped against the man, who would never forget the only nice thing anyone had ever done for him.
The man then went overseas and got busted for smuggling. He was given a choice—go to jail or let the country's scientists experiment on him with germ warfare. The experiments succeeded, and then the man, now calling himself Impasse, stole a germ warfare gun from his captors, escaped, and returned to the USA.
Impasse used his gun to infect Power Man and Iron Fist, because they had caused trouble for Caesar Cicero. He then met with Cicero and revealed both his identity and his plans to make Cicero the head of the New York Crimelords. Cicero—realizing this guy was crazy and that the attacks on Luke and Danny would bring down a heap o' trouble on his head—was terrified of Impasse.
Meanwhile, Vienna had been hired by the unnamed foreign government to retrieve—or at least stop him from using—the weapon Impasse had stolen. She set the Daughters of the Dragon (Colleen and Misty) after Cicero, who revealed Impasse's involvement. Impasse went after Maxine Lavender, the assistant District Attorney, who was trying a case against Cicero. He was driven off by Vienna and the Daughters of the Dragon—but not before infecting Colleen by contact. Vienna allowed Impasse to steal her car, which contained a tracking device.
Impasse confronted Cicero, furious over his betrayal, but was stopped from killing him by Colleen and Misty. Just before collapsing, Colleen destroyed his gun. Misty knocked him out, but was infected in the process. Vienna showed up with the vaccine, charged the Daughters $20, 000 for it, saved all those infected, and walked off.