Aggressive Solutions Int. or A.S.I., is run by a cabal of villain groups. To the people, they are some kind of Los Angeles-based public relations firm or trouble-shooting agency. But they are a front for a gang of powerful villains. All has gone well, until A.S.I. finds itself as a target of a relentless and violent vendetta by the mysterious woman calling herself Madame Mirage.
Who exactly Madame Mirage is or why she's embarked upon this campaign of exquisite revenge are the central questions at the heart of the series. While the "who" will be revealed in a timely fashion, the question of "why" will have more of an importance. Dini has said that "revealing Mirage's identity is just the tip of the iceberg. There will be clues and the more astute readers will be able to fit them together pretty quickly. One clue comes in the form of Harper, Mirage's younger sister. Mirage and Harper have a relationship not unlike Batman and Robin. Mirage is the one out dispensing justice while Harper is her backup. They both have a personal stake against A.S.I. and have devoted their lives and abilities to bringing down the evil corporation."
It was recently revealed in Madam Mirage #3 that Madame Mirage is in fact Harper in disguise. Several years before, when the sisters were working with their struggling technological enterprise, they were approached by executives from A.S.I., who sought to buy the sisters' technology, including their top secret government project, the Ellison Project. However, negotiations soured and both sisters were shot. Shortly afterwards, their father was betrayed by a colleague who turned him into the government for her own freedom and then went to work for A.S.I. Only Harper would escape to develop the Ellison project into a tool crafted around the likeness of her dead sister Angela and exact a revenge from those who had hurt her family.
Following that, Dini put the Mirage pitch in the sketchbook where it remained for years until Jim McLauchlin came on board at Top Cow as an editor, and was interested in creating a new series about a tough new heroine and contacting Paul Dini. He brought back the Mirage concept, updated it because of how many years since the first pitch, and finally he started scripting the stories.