When a New York apartment building catches fire, Daredevil arrives to help the fire department and paramedics; after he rescues Angel Jusko, a little girl who lives in the building with her parents, Daredevil's heightened hearing detects laughter in the building, and his radar sense sporadically detects the presence of a female figure in the flames, ranting "dieDIEpainPAINdieDIEpainPAIN." The figure seems to flicker in and out of existence "like smoke, blowing in the wind."
One week later, Daredevil, in his identity as lawyer Matt Murdock, is approached by the building's owner, Abraham Rutkowski, who has been accused of arson and culpability in Angel Jusko's fire injuries; the girl sustained "3rd degree burns over 75% of her body," is on a respirator due to "severe smoke inhalation," and is not expected to live. Detecting that Rutkowski's denials are genuine, Murdock takes the case and, days later, investigates the rubble of the building. The police officer who accompanies him tells him there has been "a rash of kids getting burned lately," and Murdock senses the presence of a "vaporous thing---a Vapora." After being detected, Vapora leaves the building and causes two more conflagrations, in both cases in homes where gasoline is being used for cleaning purposes and a careless spark ignites fumes.
Daredevil happens to pass by the second home, where another little girl, Laura, is trapped by flames. Vapora comes between Daredevil and the girl, warning him "GoAWAYsheISmineFORpainFORpower." Vapora seems to be on the verge of somehow merging with Laura when Daredevil, crawling on the floor in approved drop-and-roll tactics, finds a fire extinguisher and puts out the flames, causing Vapora to vanish into mist. Later, Matt Murdock proves that the fire in Rutowski's building was caused by fumes from gasoline that Mr. Jusko was using to remove kitchen tile adhesive, and Rutowski is found not guilty; Murdock informs Rutowski that Angel Jusko's condition has improved and she will be taken off of the respirator next week, although physical and psychological therapy is still needed. But Vapora seems to be lurking in the courthouse, and Daredevil knows that the danger of gasoline vapors is "only hiding. Biding its time. Waiting for its next victim."
Vapora is a semi-humanoid cloud of gasoline vapor which, like gasoline fumes themselves, can cause the slightest spark to ignite into deadly flames; although invisible to ordinary human senses, she can be detected by Daredevil's radar sense. She can fly through the air and materialize from any gasoline can; contact with water causes her to break into several miniature versions of herself, which can spread more flames and then merge into her original form. Although allegedly mindless, Vapora seems at least partially sentient and is capable of rudimentary speech; she is drawn to human carelessness and receives nourishing strength from human misery and anguish, indicating that she possesses empathic abilities. She vanishes when a fire that she causes is extinguished.