Jon is a teenaged sorcerer from the comic, The Last of the Viking Heroes. In The Last of the Viking Heroes Summer Special issue 2, he acquired a potion from his mentor, Zon, that would allow him to handle any situation when consumed. Later, at Jon's birthday party, he is given a sack of Ninja weapons pillaged "from the Orient" and some turtle soup. Thinking the soup would make the potion taste better, he mixes some into the potion.
Some brigands that Jon had angered earlier come to attack him, and he drinks the potion. With the combination of the turtle soup in the potion, and the Ninja weapons in proximity, he becomes, as his friends declare, a "Teenage Mutant Ninja Turtle." After dispatching his foes, Zon arrives and restores Jon to his human form with a blast of magic, and chastises his protégé for tampering with the potion's formula. Says Zon: “The combination of mutagen and turtles are reserved for future wizards. I believe their names will be Kevin Eastman and Peter Laird”.