Mercy is a traveler from across space and time who came to present-day Earth to stop the fate her world from happening. After the disappearance of their sovereign, Nemesis, the Nemesinian race began a centuries-long religious war between the Traditionalists (those who believed Nemesis' return was a hoax, a false prophet sent to test their faith) and the Reformers (who believed that Nemesis was the true voice of Justice and worship him as such). The war turned their once beautiful world into a battlefield.
Mercy was originally a Traditionalist who hunted down the groups of Reformers who tried to emulate the False One's teachings. When a movement began to reunite the race before they wiped themselves out, the radical Mercy believed it was a move by the Reformers to seize the homeworld. A mysterious benefactor agreed to help her bolster the planetary defenses. As the last remaining Reformers arrived the new forces, revealed as Shadow Demons from the Negaverse, began the final genocide of the race. Their leader, called the Destroyer, thanked her - it had sensed that this reunion would have forged a new galactic force for balance and justice, more powerful than any Nemesinian sovereign before and so it had sowed the seeds of distrust in the more atavistic priests, calling Nemesis into question. Mercy's reward for her assistance was to be the last to die. She fled the slaughter, unable to fight, searching for a way to travel back in time and learn the fate of Nemesis. She was aided in her cause by the sorcerous Helm of Nabu.
Nabu sent Mercy back through time to Earth so she could find Nemesis before his disappearance. Mercy materialized in Superior City, her appearance creating an energy disruption that attracted several of the cities new super-heroes. Disoriented from her journey, a confused Mercy briefly took on the appearance of Nemesis in an effort to tell the heroes her mission. Though she quickly assumed her "normal" appearance two of the heroes present, Renegade and ArcAngel (who had been teammates of Nemesis in Justice Inc.) suspected Mercy of actually being the sovereign, a suspicion that never quite went away. When Mercy learned that Nemesis had vanished months earlier she adopted elements of Nemesis' life - taking a human identity as Aya Hibino and becoming a superhero, and joining the new Enforcers of Justice. She hoped the similarity and the public exposure would help her find the Sovereign.
Renegade and ArcAngel's suspicions prevented Mercy from ever being comfortable with the team and she eventually decided to leave and conduct a more aggressive search for Nemesis. Before she could leave, however, Mercy, the Enforcers, and a group of space-traveling heroes called Starcore were transported to the anti-matter universe. Once there, Mercy was shocked to discover a group of present-day Nemesinians in league with the Weaponers of Qward. These Nemesinians were helping the Qwardians transform one of their own into a new incarnation of the Anti-Monitor. A horrified Mercy recognized this new "Anti-Monitor" as the Destroyer that would eventually kill her people. She realized that these Nemisinians were the progenitors of her order, those that had sought to return their race to the old ways by creating an imbalance between the positive and negative matter universes and thereby restore the race's power. Realizing she could not allow this to pass, Mercy attacked the new-born Destroyer, hoping to stop him before he became accustomed to his new power. Her attack proved ineffective and Mercy was killed, and her energy matrix absorbed into the Destroyer. Her sacrifice, however, gave her teammate Renegade the opening he needed to obliterate the Destroyer by turning his own energies against him.
Powers and Abilities:
As with all Nemesinians, Mercy was a living perpetual energy generator and capacitor. She could alter her appearance, fly at sub-orbital speeds, fire the characteristic black "nega-energy" blasts, exist in deep space and was essentially immortal. She could also store energy she was exposed to and could feed directly on the life forces of living beings to sustain herself if necessary.