On returning to his kingdom of Latveria after a successful revolution against him, its monarch, Doctor Doom encountered a young boy named Kristoff and his mother, a Latverian woman still loyal to Doom. A robot under the control of Zorba, the current ruler of Latveria, slew the woman for violating curfew, thereby outraging Doom, who considered the woman to have been under his protection and destroyed the robot in retaliation. After regaining the Latverian throne, Doom took the orphaned Kristoff under his care and had him raised in the royal palace. Doom became quite fond of Kristoff and decided to make him his heir.
Later, Doctor Doom's body was destroyed by the explosion of cosmic energy in which the alien Tyros, formerly known as Terrax, perished. Doom survived by psionically transferring his consciousness into the body of an onlooker just before Doom's own body was destroyed.
Back in Latveria, Doctor Doom's robots, believing their master to be dead, implemented a plan of his by which Doom hoped that his legacy would carry on after his death. The robots began programming Kristoff's mind with the recorded memories of Doctor Doom in chronological order. As a result Kristoff came to believe that he himself was the original Doctor Doom. Upon receiving the memories of Doom's first partnership with the Sub-Mariner and Doom's theft of the Baxter Building, the former headquarters of Doom's arch foes, the Fantastic Four, Kristoff commanded that the programming stop. Seeing where that plan to destroy the Fantastic Four had gone wrong, Kristoff resolved to try it again, but this time to make it work by avoiding the mistake of involving the Sub-Mariner.
Kristoff garbed himself in a variant version of the original Doctor Doom's armor. This armored suit was designed so as to make Kristoff appear to be the size of an adult. Kristoff decided that the reason he possessed a child's body was that his consciousness had been transferred into it by an enemy.
Using the original Doctor Doom's advanced technology, Kristoff entrapped the Fantastic Four within the Baxter Building, drew it outside Earth's atmosphere, and then blew the building up. However, the Fantastic Four survived by means of the Invisible Woman's ability to generate protective force fields. The Fantastic Four invaded Latveria and defeated Kristoff. Learning to their astonishment that the Doctor Doom who had tried to kill them was really a small, brainwashed child, the Fantastic Four took Kristoff back to New York City with them in the hope of restoring him to his normal personality.
Eventually Kristoff, still believing himself to be the original Doctor Doom, was placed in confinement at Four Freedoms Plaza, the Fantastic Four's new headquarters. Meanwhile, the entity calling himself the Beyonder restored the real Doctor Doom to his original body.
Subsequently, the real Doctor Doom used one of his robots to kidnap Franklin Richards, the son of Reed and Susan Richards of the Fantastic Four, in order to use his powers to battle the demon Mephisto. Kristoff summoned the robot and had it free him from captivity and transport him to Latveria, where he donned a suit of his special armor. He then confronted the real Doctor Doom as the latter was using Franklin as a pawn in bargaining with the demon Mephisto for the soul of his deceased mother, Cynthia. When the real Doctor Doom admitted to a human weakness - his inability to trust Franklin to defeat Mephisto in combat, Doom's robots decided that he could not be their true master, and that Kristoff must be the true Doctor Doom. His robots having turned against him, Doctor Doom was forced to flee Latveria.
Kristoff, as Doctor Doom, was then ruler of Latveria, and believed that it was the real Doctor Doom, whom he believes to be an imposter, who has entrapped him within a child's body. This began a long civil war between the two, as one or the other were deposed and set up as the true Doom, and often came to blows personally. Then, during their last encounter, Doom uttered a code word that returned Kristoff’s true personality. Doom then placed Kristoff into stasis in a Tibetan monastery-lab under his control.
Much later, Kristoff was awakened by Nathaniel Richards when Reed Richards and Doctor Doom were presumed dead. Nathaniel was actually after Boris, Doom's former guardian, in an adjoining stasis chamber, who was actually the Tomorrow Man in disguise. Kristoff returned with Nathaniel and Sue Richards to the Fantastic Four and joined them on several adventures, becoming a close, but carefully watched, associate. Kristoff soon developed a crush on Ant-Man's young daughter, Cassie.
When the Fantastic Four seemingly perished fighting the menace known as Onslaught, Kristoff teamed with Nathaniel Richards in securing the Fantastic Four's equipment in the Negative Zone before returning to Latveria to assume the vacant throne. Somehow, Kristoff was blocked from entering by the Dreadknight, and fled with Nathaniel, vowing to return.
-To be added
The Future Foundation
A unspecified anount of time later suffering from brain damage Doom had inflicted upon himself during the Fall of the Hulks impairing his ability to rule, Doctor Doom summoned Kristoff from exile. Kristoff would be crowned the new Monarch of Latveria with Doom advising from the shadows. When Doctor Doom regained his intellect, he became the Monarch of Latveria once more.
Kristoff Vernard was with his adopted father, Doctor Doom when they were attacked by a mysterious group known as The Mapmakers. Kristoff and Doom were able to fight off The Mapmakers while the Illuminati destroyed the other Earth.