A former schoolmate of Bruce Banner, Sterns develops a deranged love/obsession with Banner's "career" as the Hulk. Sterns subjects himself to a multitude of experiments involving gamma-radiation to emulate his "hero". This results in Sterns turning into a distorted monstrosity possessed of vast superhuman strength, and develops schizophrenia. From this point, a much stronger, arguably deranged, personality gives him ‘orders’ to carry out.
Calling himself Madman, Sterns hatches a plot to kill the Hulk, giving him a poison injection that rapidly deteriorates his physical state. This puts the Hulk in conflict with various members of his rogues’ gallery, most notably the Abomination, turning weaker and more emaciated for every battle. Samuel Sterns, the Leader, and Phillip's brother, comes to the Hulk's aid and helps him track down Madman to find the antidote. He explains that Madman "scares him", but can’t force himself to kill his brother. During the ensuing battle, Madman suffers a psychological breakdown, completely submerging his original personality, and Hulk manages to cure himself, as well as poison Madman, leaving the latter on the verge of death, with the remedy dropped barely out of reach.
Later Madman reveals that he simply increased his mass to grab it, and used the time to masquerade as a researcher in the Red Skull's "New World Order" organisation. He here helped to engineer the transformation of a captured S.H.I.E.L.D. agent into the power-mimicking creature known as Piecemeal, and installed a safety override, making it answerable only to himself.
When tracking the creature he found it in confrontation with the Hulk in the vicinity of Loch Ness, and knocked out his enemy from behind. He dumps the Hulk into the lake saddled with iron weights, but is disappointed when the latter takes longer than expected to escape. During the ensuing gang-up Madman continues to make disorderly, deranged remarks. When Perseus, a retired Pantheon member the Hulk was visiting, tries to intervene, Madman indifferently kills him, but the Hulk punches him away.
While the Hulk seemingly kills Piecemeal, Madman decides to take off in a stolen jet. The Hulk overtakes and starts to dismantle the jet, and Madman's triggers a pilot-chair parachute, remarks that he's not interested in killing Hulk, since it would be dull to not annoy him anymore, and detonates the plane.
After landing in London he immediately holds the British prince Charles hostage on top of Buckingham Palace, and demands to be declared king of England. As Hulk comes to the rescue, Madman states that the latter should understand the demands to use great power and shifts from crying to irreverently upbeat within seconds, dropping the crown prince towards the ground. The Hulk catches up, while Madman is in the middle of a temper tantrum about everybody "ganging up on him", and manages to knock him down. Madman once again voices his "love"/admiration for Hulk/Banner, but takes the opportunity to escape as the London Bridge collapses underneath them.