A cruel and merciless mercenary, Blackjack O'Hare sold his services to the highest bidder. Working for the malicious mole, Judson Jakes aboard Spacewheel, O'Hare and his Black Bunny Brigade launched a raid on the Cuckoo's Nest and stole Gideon's Bible for his employer. He also kidnapped the girlfriend of Rocket Raccoon at his master's behest. When Rocket was informed Lylla had been taken to Spacewheel, he and Lylla's uncle, Wal Rus, left immediately with their new found friend, the Hulk, to rescue her. Blackjack thought he was safe while he was holding Lylla hostage, but the tremendous strength of the Hulk coupled with the astonishing speed of Rocket Raccoon was enough to overpower him.
Whether it was that defeat or a higher payoff which led him to work for Lord Dyvyne was inconsequential. O'Hare was working against his former employer. Blackjack, and his Bunny Brigade, was again commissioned to kidnap Lylla for Dyvyne, so the reptilian toy mogul could obtain her fortune for himself. However, always looking for the big payday, Blackjack betrayed Dyvyne and decided to keep Lylla for himself. Outraged, Dyvyne sent his deadliest creation, the Red Breath, to destroy O'Hare as well as his other enemies. Meanwhile, Judson Jakes deployed a squad of Killer Clowns, flying on Vacuusleds, to do the same. O'Hare and his Black Bunny Brigade were caught in the middle of two warring factions, and the result was the annihilation of every Bunny Brigade member, save Blackjack himself. Fearing for his life, the sole surviving mercenary struck a deal with Rocket Raccoon, and the two became temporary allies.
Rocket used O'Hare's knowledge of the seedier places on Halfworld, such as his familiarity with the Wild Worms of Halfworld, to escape persecution, but as soon as he got a chance, O'Hare double-crossed Rocket and his allies. After a chance meeting with Uncle Pyko in a robot bar, O'Hare assembled eight other miscreants to join his insane quest for redemption. He thought if he could recapture Lylla, and Gideon's Bible – now in Uncle Pyko's possession – and bring them back to Lord Dyvyne, he could get back in his employer's good graces. Rocket and the others weren't about to let that happen. They quickly defeated O'Hare's impromptu group, and escaped without a scratch. O'Hare was left empty handed once more.
Blackjack didn't show his face again until Rocket was staring death in the eyes. The savior of Halfworld was saved in the nick of time by the former leader of the Black Bunny Brigade. When asked why he did it, O'Hare merely said there'd be no need for a merciless mercenary if Rocket Raccoon was dead. Blackjack continued to fight alongside Rocket and Wal Rus against the combined forces of Judson Jakes and Lord Dyvyne, and he even left Halfworld with Rocket Raccoon in search of more adventures, but is it only a matter of time before a huge sum of money lures the rabid mercenary back to the side of evil? The answer has yet to be revealed.