While most of David Clinton's costumed career as Chronos was spent utilizing cheesy clock-themed weaponry versus his arch-enemy the Atom and, later, his foe's teammates of the Justice League... his hidden passion was to master the flow of time to his will. Although he used various criminal endeavors, by solo and alongside the Injustice Gang and Crime Champions, to obtain the finances in order to build his ultimate time machine... such was years from fruition. After a series of defeats, David seemed to submerge himself into his research away from friend and foe alike.
To that end, under the tutelage of the mysterious "Doctor Fox" (or rather, journals left behind by this temporal apparition), Clinton was enticed by the enigmatic Power Broker into defeating the World's Finest heroes in order to unlock the secrets of Fox's research. Apparently, this powerful being held the key that his new lackey had been searching for throughout the years.
In order to gain this key, Chronos sent time bombs into the past to lure Superman away, while enticing Batman to change his own personal history and save his parents. His goal, and that of his master, was to have both caped crusaders alter history so that they no longer existed, thereby removing the threat they displayed to evil. Still, the dynamic duo shrugged off such efforts on Clinton's part, forcing him to retreat from them into the time stream, seemingly never to return. Or did he?
On Earth-Two, David's counterpart Kale was not as intelligent yet still managed to assist to time traveling tyrants in Per Degaton and the Ultra-Humanite. As a result, three versions of Kale exist in the time stream of that world, which corresponds to Chronos, Fox and the Power Broker. All three appear to be the same man, with Fox a version of Chronos in the past having gained knowledge while the Broker remained in the future to secure power through his present day version. None of these ultimately obtained what they all wanted, complete mastery of time and space.