King was the leader of the Royal Flush Gang.
When King was about Jack's age, Batman broke up the Gang for some time. Consumed by anger and humiliation, he waited years to exact his revenge. King eventually went back to Gotham City, now as the leader of the group, and on their first holdup on a yacht he met the new Batman.
King seemed to be more cold-blooded, and even homicidal, than the other members. When they broke into a museum and were intercepted by Batman, the Gang took someone hostage. During their escape, King ordered Jack to drop the hostage from midair. He didn't tolerate any disrespect or defiance from anyone — even from his family. He admonished Melanie for her lack of focus during the museum heist, and told her to leave the family if she wasn't fully committed.
Later that night, the Gang returned home from a pulled off heist. However, King was disappointed in the fact that Batman hadn't shown up, for he had saved a card especially for him. Nevertheless, King got to use his deadly gimmick moments later, when they found out that Batman was inside the premises. King engaged Batman in an aerial mêlée, and even managed to cut off his right wing, but soon lost the upper hand when he collided with a balcony. He requested Ten's help, who hesitated long enough for the GCPD to show up and take the Gang into custody.
Proof of Love
Afterwards, King's confidence in Ten was considerably shaken. So, he concocted a plan in order to test his daughter, and to be sure where her allegiance lied. He staged their abduction at the hands of the Jokerz, and sent the ransom to Ten, instructing her to raid a big poker game — the Derby. When Ten did as instructed, King told her that despite loving her, they had to make sure she loved them too. Ten accused King of only wanting an accomplice, and not really loving her. At that time, Batman interrupted the family feud, and a skirmish ensued. However, Batman had forewarned both the Derby gangsters and the GCPD, and King was quickly surrounded and outnumbered. Then, he surrendered himself to the authorities.
The Gang eventually escaped, and took shelter at Casino Palace. However, now they operated with one member short: Ten. King had completely forsaken his daughter and forbade his family from ever mentioning her again.
Tension grew as King failed to provide for his family with the same lifestyle they had been used to. Queen constantly compared King to her father, the former leader of the Gang, whom she had in high esteem. Tired of being berated and diminished in comparison to his predecessor, Queen decided to quit. The perfect chance presented itself when the Gang was hired by Paxton Powers to steal precious artifacts. At some point, King had become acquainted with Paxton's personal assistant Sable Thorpe, and the two cavorted and conspired to poach Paxton's illegal priceless collection.
King and the Gang broke in a museum to steal an exquisite effigy. While Jack was disarming the surveillance system, King slugged him for evoking Ten, and the alarms went off. It remains unclear whether that was intentional or not. Shortly after, Batman showed up, and during the getaway, Jack was left behind and arrested. King then met with Paxton to collect his fee, but the he only got a meager payment, because the artifact was damaged. This provided him with the perfect excuse to enact his plan. King decided to abduct Paxton and demanded a pay of 20 million credits.
Paxton guaranteed that his money was frozen in investments, so King called Bruce Wayne and asked him for the ransom. When turned down, King became aggravated and raised his sword against Paxton. In such moment of despair, Paxton told King about his valuables, namely the Crown of Takal that was worth what he was demanding. King wanted Sable Thorpe to go and pick up the Crown, but Queen distrusted Paxton's associates, so she suggested for Bruce Wayne to collect the trinket himself. Afterwards, Paxton made an enticing proposition: King would assassinate Wayne in exchange for millions of credits. After giving it a thought, King accepted.
At some point, King secretly passed the security codes on to Sable Thorpe, who plundered the entire collection, while the others were busy with the transaction.
As soon as Bruce Wayne delivered the ransom, King tried to do away with him. However, he didn't expect the old man to put up a fight, and failed in his attempts. Then, he was tackled by Bruce's mutt, Ace. After wrestling with the dog for a few minutes, King seized an opportunity to snatch the priceless crown and flee, leaving Queen to her fate.
He headed back to his hideout, where he met with Sable, and the two boasted of the well-succeeded plan. At that point, Queen, who had eluded capture, cut their assignation short and attacked her deceitful husband. King took her on and tried to escape, but was thwarted, and after another fight, seized by Batman. King was presumably returned to jail.