Zack Overkill and his twin brother Xander were super-powered mercenaries. They committed crimes for the money, not concerning themselves with any innocent deaths. Their boss, Black Death was soon arrested and ordered the execution of his henchmen which he didn't trust. A trap was set and in a warehouse, were gunned down by a rain of bullets from all directions. Xander was killed, Zack testified against his boss and entered the Witness Protection plan. As part of his parole, Zack must take drugs that suppresses his super powers. Working as a mail clerk in an office, Zack is bored out of his mind.
When news of a freak tornado hit downtown, Zack knew things weren't as they seemed. Going to the scene, he recognized the signs of a battle that had been covered up with the explanation of a storm. He couldn't give in to the feeling of slipping away into a weak individual living a lie. He decided to take drugs to cope with his mundane life. A dealer had a drug that would hide the effects of drugs when tested. Zack decided to float through life and laugh at the idiots.
Laughing to himself on his way to his car one day, a woman on her cell phone assumed he was laughing at her and her conversation. She told him off saying he was a loser that thought he was better than everyone. Zack was pissed since she didn't even know who he was. To his amazement, he tore off the door to his car. His powers were back. It seemed the drug he was taking to cover his use was having a reaction with those the government made him take.
Zack decided to put on a mask and just roam the night. Coming across a woman getting attacked in an alley, he decided to do something about it. He didn't care one way or the other for the woman but enjoyed the rush of excitement after taking part in a violent act in putting the guys down. Zack felt stronger. He always shared power with his brother. Now it felt like he had inherited his dead brother's power and had become stronger than ever.
With this, the scientist responsible for performing the tests on Zack and Xander receives an alarm that "Project Overkill" has moved back to active status.
the scientist reveals that Zack and his brother, Xander were only clones. and all memories they had from their childhood were implanted. Wanting Zack back for experiments and further cloning, he sends two super powered henchmen after Zack, which he brutally kills.
Later he is found by his brother Xander's girlfriend, Zoe Zepplin, and they travel to find the professor responsible for creating Zack and Xander. however, the professor sets a trap for them and ages Zoe Zepplin to the age of 80. Zoe Zepplin still manages to kill the scientist, and free Zack Overkill before her imminent death.
Black Death now releases Zack overkill's clone. a "triplet" to Zack and Xander and he draws out Zack by holding a bank building hostage. Zack manages to get inside and a battle ensues. since they both share feelings, each hit landed resonated out to both, so in a last-ditch effort, Zack tackles his doppleganger out of a three story window, and kills his triplet.
afterwards, Black Death is visited in Prison by Zack Overkill, and Zack makes clear that he will murder Black Death. Zack then is offered a job with the SOS program, and becoems a secret agent.
Now working for SOS, he is given an assignment to go rogue, so he can be undercover and infiltrate the community of villains, called Level 9. After finding out that there is someone taking the name of "Lazarus" who is systematically wiping out the Supervillains, SOS incorrectly believes that Zack had indeed gone rogue and he is imprisoned in the same prison as his old boss, Black Death. Lazarus, is revealed to be Xander's brother, back for vengeance.
Powers and Abilities
Zack and Xander share their super strength and durability, however, now that Xander is dead, Zack has gained the totality of his powers. He is able to effortlessly rip off a door from a car, flip a car, and punch through Brick walls and metal.
His durability is effective against blunt and physical force, and as he is resilient against bullets, they will still peirce and be fatal to his person.