Lorraine Reilly is the daughter of Senator Walter Reilly, whose political rivals originally kidnapped her in order to perform a test to see if a nuclear accident identical to the one that created Firestorm could create other nuclear-powered beings. She was put in a senses-deprivation chamber for an extended period of time, eventually becoming deprived of any willpower. She was then subject to a nuclear explosion, and her meta gene was activated. She was given the ability to create and control nuclear fire, most notably as wings coming out of her arms.

She was then pitted against the Nuclear Man until he reminded her of who she really was. She then turned on her creator, Henry Hewitt, who had already begun the same nuclear experiment on himself, creating Tokamak. Firehawk and Firestorm eventually overcame Tokamak, and served as partners thereafter. The romance that developed led to problems for the Nuclear Man, since Ronnie was in a relationship already, and Martin was not necessarily interested in Lorraine; also there was an issue with the significant difference in ages, as Lorraine was in her mid-to-late twenties, Ron was in his teens, and Martin was in his late forties. Nevertheless, the two heroes remained virtually inseparable for much of Firestorm's second series.

Lorraine made sporadic appearances for years, eventually renouncing her Firehawk persona during the events of Identity Crisis, so disheartened with the superhero community and all that comes with it. Focusing on her civilian identity, Lorraine began following in her father's footsteps, politically. She reappeared in the most recent incarnation of the Firestorm series, investigating Jason Rusch's role in the new Firestorm Matrix, inadvertently triggering the reemergence of the Ronnie Raymond aspect of the Matrix. Thereafter she served as a mentor and associate to the current Firestorm, even suggesting him to membership in Donna Troy's space team during Infinite Crisis. Following in the wake of Infinite Crisis, she formed a part of the Justice League debacle during 52, but managed to save her public image enough to be elected to the Senate, filling her father's chair.

Though her relationship with Jason has been somewhat strained recently, it seems as if the two are on somewhat better terms recently.

Powers Hewitt's experiments transformed Reilly into a human capable of commanding nuclear forces on a molecule level and turn it into heat that can be used in a number of ways. She can create huge amounts of heat energy that can melt most metals and materials. With a thought, she can generate enough heat to cause nearby objects to spontaneously combust.

When transforming to Firehawk, Lorraine's clothes metamorphoses into a costume and she uses her power to create "wings" which enable her to fly. Surrounding her wrists, calves and hair is a blue fire which works protectively, shielding those areas with an intense heat.