Slapstick has fought foes such as the Nuclear Bum and Overkill alongside other heroes like Spider-Man.
Slapstick was originally class clown Steve Harmon. In a plan to get back at his arch-rival Winston, Steve dressed as a clown to blend into the crowd at a strange new carnival.
Before Steve could enact his plan, Winston and his date, Heather, were kidnapped by several clowns. Steve picked up a mallet as a weapon and followed them. The group entered the carnival fun-house and entered a portal disguised as a mirror. As it was closing, Steve followed.
His molecules stretched across 3741 dimensions and Steve ended up in the realm of the Scientist Supreme of Dimension X (who resembled Groucho Marx). The scientist helped Steve master his new form, a body composed of living unstable molecules dubbed Ectoplasm. This essentially made him a living cartoon character. The scientist, who had been ousted from his position by the Overlord, theorized that Steve had come to his new form because he was slightly out of synch when entering the fun-house portal.
Using his new powers and a map the scientist had, Steve freed many captive Earthlings from the evil Clowns from Dimension X and their ruler, the Overlord. It was learned that this was what the scientist had intended all long. The Overlord's plan had been to brainwash Earthlings enough so their belief would be sufficient to give Overlord whatever he desired. The Overlord's plans were foiled when the belief that held up his castle gave way as the humans regained their right minds. The castle crashed. The captured humans ran to the portal, followed quickly by the monstrous clowns. Steve destroyed the mirror, eradicating the clown's influence on this reality.
Minutes afterward, Steve was found by his best friend, who agreed to assist him. Since he arrived on earth, he became friends with many people, such as Ghost Rider.
Steve had other villains to confront: a Punisher copycat called the Overkiller attacked Steve simply because he was different. The two fought in a mall, destroying most of it. Steve ended the fight by literally kissing Overkiller and then walloping him while the man reacted with disgust. Spider-Man assisted with the battle. There was also a homeless man, the Neutron Bum, with the power to cause explosions. The vagrant was furious over the price of coffee and decided to take it out on society by blowing up random parts of New York, such as a local Tower Records. Neutron Bum, despite his fixation on the unfairness of high coffee prices, seemingly could not keep the actual price of it straight. Despite the gathering of dozens of superheroes willing and planning to fight the man, Slapstick simply neutralized the situation by getting Neutron Bum what he had been yelling for all along, a cup of coffee (and then blindsiding the man from behind while he was drinking it).
He was a friend of Speedball of the New Warriors and was described as "The hero who doesn't fight crime but rather plays cruel tricks on it."
Later, Slapstick teamed up with the New Warriors to fight Dr. Yesterday, partly because doing so would impress women. He wasn't seen for some time. It was established that at some point prior to Justice and Firestar leaving the New Warriors to become Avengers, Slapstick and Ultra-Girl were made official members of the Warriors and given communicators, after helping the team stop a Badoon invasion.
Slapstick helped the surviving members of the New Warriors find Hindsight Lad, the young man and former Warrior responsible for outing the secret identities of past Warriors and allies to the public. LaFroyge was stopped, arrested by the authorities, before Slapstick's identity was made public.
Slapstick was later seen on the bus of new recruits arriving at Camp Hammond as part of the Initiative training program. He was later seen, with other heroes, confronting Thing as part of a training mission.
Slapstick and other Camp Hammond members were sent out as crowd control when the Hulk led an attack on New York. Slapstick and other members were imprisoned by Hulk's forces in Madison Square Garden and neutralized with power-sapping technology. They were rescued by black ops forces associated with the Camp. In a recent issue of the The Initiative, it was shown that it was Slapstick who attacked and almost killed the Gauntlet out of loyalty to the New Warriors, in retaliation for Gauntlet's use of the team's name as an insult. He had since tried to admit this to his teammates but was almost comically interrupted. He later came in possession of a device containing the memory and personality of KIA, villainous clone of Michael Van Patrick, and decided to keep him away for further use.
Slapstick and several other former New Warriors recently were recruited by Justice and apparently deserted from the Initiative, after Justice found evidence of shady activities within the organization. After helping to stop KIA's rampage, this new group officially quit the Initiative, intending to act as a form of independent oversight for the program; as legally registered heroes, they were free to act unless they broke the law while doing so. When asked to change to his less conspicuous normal form, Slapstick admitted that he had not done so since joining the Initiative, and claimed that the mechanism that activated the change no longer works.
Slapstick's body is made out of unstable molecules, making him invulnerable. A device in his left glove helps him stay cohesive, as well as allowing him to turn back into his normal form. Being hit with electricity or struck by lightning seems to make Slapstick much more powerful and sillier. Slapstick has Cartoon Physiology, meaning he can manipulate himself in impractical and outrageous ways.