Phillip Sterns was fascinated by the intelligence of Bruce Banner and wanted to follow in his footsteps as a nuclear physicist. Although the smarter one in his family, Sterns could not compete with Banner's brain even though he attended the same graduate school. He completed his courses near the bottom of his class, but no matter what job he managed to secure, Sterns always kept track of Banner's exploits. Phillip even believed that Bruce had stolen his idea of using gamma radiation as a weapon. He knew of Banner's accident that turned him into the Hulk, and he believed the power should have been his. Sterns spent years trying to duplicate the process to obtain the powers of the Hulk, and he eventually succeeded, but the creature he unleashed proved to be Phillip's undoing.
Madman to Phillip was much like Hulk is to Bruce. A separate personality that wanted control, only Madman was much smarter and more aggressive than his alter-ego. It was very easy for Madman to manipulate Sterns into doing his bidding for him. Such was the case when Bruce came to work at a nuclear research facility disguised as a janitor. Phillip immediately recognized Bruce, and Madman devised a plan to kill him. A poison was to be injected into Banner, and that would be his end. Unfortunately for Sterns, after he injected the poison, the Abomination attacked the building and forced Banner to transform into the Hulk. It was the Hulk's healing factor that ultimately gave him time to slow the effects of the poison. The two behemoths fought leaving Hulk as the victor after dropping the Abomination into several vats of toxic waste. Banner, in his gray incarnation, retained his intelligence and knew he was dying, so he sought the help of Reed Richards to determine what was killing him. Reed was at a conference with the rest of the Fantastic Four when Bruce found him. The Hulk, being the Hulk, entered in a threatening manner which caused a brawl between he and Ms. Marvel in her mutated personification of a She-Thing. Hulk suffered a heart attack and collapsed during the fight, and eventually Reed examined him only to find the poison was unlike any he had seen before. The toxin constantly mutated in order to keep his immune system from fighting it off. In other words, Madman was going to succeed in killing the Hulk.
The Hulk returned to the facility where he last saw the Abomination, thinking he knew who was behind the evil plot, but before the Abomination could answer, Hulk was transported to another place by his archenemy, the Leader. Hulk was not too happy to see his foe, but his attacks were thwarted by the Leader's Riot Squad, a group of gamma powered individuals that served as his guardians. Tremendously weakened, Hulk had no choice but to listen to reason and soon found out who the mad man behind his current situation was. The Leader told Banner of the sad story of his brother, Phillip Sterns, but he made Bruce believe that Phillip and Madman were two separate entities instead of one being. The Leader also revealed that he was responsible for sending the Abomination to attack the research building, so he would force Banner's change into the Hulk, ultimately saving his life. All of this was done so the Leader could ask the Hulk to kill Madman because he feared Madman would come for him too. Leader transported Banner to Madman's location, and the final battle had begun. Hulk found out about Stern's grudge against Banner, and that he and Madman were actually the same person. Madman brutally assaulted his enemy, but the Hulk wasn't about to lie down and die just yet. Sterns gained control of his other personality and told Hulk where he could find the ring that poisoned him, but Madman reasserted himself when Phillip was about to expose the antidote's hiding place. The struggle between the two separate personalities was fierce, but the Madman persona won out, and the man who was Phillip Sterns ceased to exist. While Madman was distracted, Hulk injected Sterns with the poison before he could revert back to his superhuman form, and now the two of them were in the same boat. Hulk feigned unconsciousness while Madman retrieved the cure, and then Bruce stole it for himself. As Hulk transformed back to Banner, he administered the remedy and was healed. As for Madman, he was now dying and pleaded for Bruce to save him. Bruce left the antidote several feet away from him and walked away, leaving Madman's fate in his own hands.
Apparently, Madman was able to reach the syringe containing the cure because he returned as Hulk was visiting Scotland investigating reports of a monster in Loch Ness. The monster turned out to be an escaped experiment of the Red Skull called Piecemeal. Madman helped the android subdue the Hulk before revealing he was disguised as a scientist inside the Skull's New World Order during Piecemeal's creation. Madman implanted an overriding mechanism inside the robot in order for Piecemeal to be subservient only to him as well as a tracking device, which is how he found him. When the Hulk recovered, Madman and Piecemeal fought together against their common enemy, but Madman made a grave miscalculation when he killed a retired member of Hulk's group, the Pantheon. The man, once known as Perseus, attempted to assist the Hulk, but Madman slammed his skull into the ground, murdering him. In his rage, Hulk easily defeated Piecemeal, and Madman fled to England. Hulk gave chase only to find Madman demanding to be made King of England by holding the Prince of Whales hostage. With an assist from Killpower and Motormouth, Hulk saved the Prince and defeated Madman but not before Madman confessed the only reason why he caused so much trouble for Hulk was because he loved him. Madman fell into the Thames River when London Bridge went falling down, and his body was never recovered. Hulk doesn't believe Madman perished in the fall.