Artist Jonathan M. Sweet based the character's physical look after the Batman foe Dr. Hugo Strange, particularly the bald, misshapen head and thick glasses. The name "Fruitcake" is an apt syllogism for "strange", referring to a crazy person. The name may also be a nod to "Sigmund Fruitcake", a character from the live-action bumpers on The Super Mario Bros. Super Show!. Both names are parodies of Sigmund Freud's.
Another influence was Prof. Norton Nimnul, another mad scientist character from Disney's Rescue Rangers who possesses a similar lumpy-looking head and glasses and who often concocts a series of crazy, improbable schemes for world domination.
Ostracized from the legitimate scientific community for his radical ideas in genetic therapy, Prof. Fruitcake quickly found a home with Hiss Hole and the Clan as the team's science officer. Fruitcake's many innovations include the mind-control punch in issue #3, the mutagenic missile in #9, and the stem-cell research that created the evil clone Demi-Jon. He considered creating an Angela clone; however, as the first clone had been a failure, he decided to scrap this plan.
In #17 the professor inadvertently turned Josh and Jon into a pair of human/plant hybrids by spilling a sample of an unstable experimental botanical enzyme on a frayed electrical wire, where it ignited. Fruitcake and Hiss Hole escaped, though Josh and Jon were caught in the resulting explosion. Though the building was destroyed they were thankfully unhurt--but the air was filled with ionized spores. The boys inhaled them, as well as got some on their skin, causing them to turn into a pair of plant mutants (who looked very similar to the Darkwing Duck villain Dr. Bushroot). Hiss Hole wanted to exploit this happy accident by using their mutated DNA to breed a race of plant people. He tried to lure them into a trap, offering them a sample of the chemical which could be used in a cure. Josh and Jon went to see Hiss Hole, and, carefully dodging his trap, managed to secure the mutagen they needed to become normal again. Afterwards they turned Hiss Hole and Fruitcake over to the police, and they were jailed.
In #30 Fruitcake planted thousands of minature cameras all over the neighborhood, including the Sweet house and Josh's lab, to study the Warriors' technology for possible evil applications. The cameras were discovered and destroyed--plus his boss presumably punished him for the great expense of purchasing unauthorized equipment.
In #33 the clan posed as doctors to get to Jon, who was in the hospital for surgery. Fruitcake used a bizarre device of his own making, the hypodermic bazooka, to try to shoot Ben and Flunger with dozens of hypodermic needles filled with a sedative. The device backfired, however, shooting Fruitcake full of needles and knocking him out.
In chapter three of "Up the Demi-Jon Staircase" Demi-Jon mentioned Fruitcake has since reformed. In "Feminazi" (#51) Jon and Josh trace a credit card used to purchase Feminazi's battle armor to "Fryden Caysuite", which turns out to be an alias of the professor's. Fruitcake, who now works as a handyman in a low-rent apartment, seems to show no desire to return to his evil ways and even agrees to help the boys on the condition that his name isn't given to the police. He had become the victim of identity theft himself, he says, when a contact he had made during his criminal days broke into his lab, hacked his computer and stole the plans he had for a cyborg, as well as wetware chips he had developed to control said creature (now going by the name Feminazi and far divorced from his original vision.) He wishes only to see the person who stole his ideas and technology punished.
Though not technically a mutant, Fruitcake is somewhat short and hunchbacked, as well as blind in one eye. He has an oddly-shaped, bald head with tufts of greying hair going every whichaway, a bushy beard, and a kinky mustache that sticks out at the ends. He is noticeably bowlegged and has clawlike fingers, suggesting he may suffer from rheumatoid arthritis. He seems to have only one tooth in his mouth. He usually wears a pair of green plaid pants and a bloodstained lab coat. His accent was originally a mixture of German and jive, though the latter has been dropped.
Hiss Hole seems slightly nicer to Fruitcake than he does his other mutants, as he values the man's intelligence and ingenuity. However, he has been known to snap at the professor too if things don't go his way.
- "Hiss Hole Comes to Town"
- "A Fair Fight"
- "A Girl and Her Chair"
- "Soul Feud"
- "Dizzy Doctors"
- "Plant Feud"
- "The Nefarious Four!" (nonspeaking appearance)
- "Feminazi" (reformed)
- "Up The Demi-Jon Staircase" (mentioned only)
He is the only villain to appear as a host in a wraparound segment (#30, Oct 2007)