Together, the newly formed pair avenged the death of Devil’s family and went on a series of adventures together in Dinosaur World. They even managed to repel an alien attack that would have wiped out the Small-Folk, despite the way that Moon-Boy was rejected by his people. The King of the Monsters was briefly transported to the Valley of the Flame, where he met Devil in battle before teaming up with him against the Lizard People.
While Devil and Moon-Boy had prior encounters with residents of the prime universe, their first extended stay on Earth came as members of the Fallen Angels. An alien mutant named Ariel recruited them to the team, and teleported the duo from Dinosaur World to Earth. Devil and Moon-Boy felt camaraderie with their new teammates and enjoyed their time among them. However, Devil was struck with immense guilt when he accidentally stepped on and killed Don, a cybernetically-enhanced lobster who was also a member of the team. When the Fallen Angels disbanded, Devil and Moon-Boy returned to their home.
Devil and Moon-Boy had two adventures alongside Slapstick and Excalibur on Earth before they were seemingly stranded there by one of Jennifer Kale’s attempts to send Howard the Duck to his homeworld. Ghost Rider subdued the friends after they were set loose in New York City, but they were left without any way to return to Dinosaur World. Soon after, Devil and Moon-Boy were brainwashed by the Ringmaster into joining his Circus of Crime. Spider-Man was able to free the heroes from the Ringmaster’s grip, and they were subsequently given a new home in the Savage Land.
Devil quickly acclimated to the Savage Land, but his peace was shattered when the Heroes for Hire were sent by S.H.I.E.L.D. to retrieve Moon-Boy for scientific study. Inexplicably, Devil had apparently laid eggs, and he reluctantly chose to protect them rather than save Moon-Boy. For several months, Moon-Boy remained a captive of S.H.I.E.L.D. while Devil became increasingly despondent over his friend’s fate.
Stegron the Dinosaur Man felt great sympathy for Devil’s plight and feared for his survival if he was not reunited with Moon-Boy. To save Devil, Stegron came to America and began attacking S.H.I.E.L.D. installations until he was taken down by a team of young heroes in the Avengers Initiative. However, when they learned why Stegron had come so far, Reptil and his team secretly broke Moon-Boy out of custody and reunited him with Devil in the Savage Land.
Some time later, Devil and Moon-Boy joined forces with Skaar and Ka-Zar when Shanna the She-Devil was possessed by the Designer, the creator of the Savage Land. They ultimately succeeded in defeating the Designer and freeing Shanna from his control. After that, Moon-Boy and Devil apparently made their way home, before once again encountering their mutual enemies, the Killer-Folk.
Moon-Boy suffered a fatal beating at the hands of the Killer-Folk, who had somehow acquired a Kree Omni-Wave Projector which they called the Nightstone. Moon-Boy’s killers fled through a portal to the Marvel Universe, while Devil reunited with his friend one last time. As his final wish, Moon-Boy asked Devil to follow the Killer-Folk and avenge his death. Devil went through the portal and emerged in modern day New York City.
During Devil’s first encounter with Lunella Lafayette, she was successfully able to lead him away from the New York Police and into a safe location. Once there, Luna revealed that she had been tracking the Omni-Wave Projector because she believed it was the only way to protect herself from the Inhumans’ Terrigen Mist and prevent her body from undergoing the unpredictable Terrigenesis. Although Luna tried to convince Devil to stay hidden, he sprung into action when she was captured by the Killer-Folk.
Devil was able to free Luna from captivity, but their activities together were broadcast on TV. This alerted Luna’s parents to her hidden superheroics, and they tried to prevent her from doing it again by harshly grounding her. Undeterred, Luna still managed to hide Devil in a secret laboratory beneath her school. That allowed them to save Luna’s classmates when a fire broke out, but Devil was subsequently blamed for the damage by Amadeus Cho, the latest hero to become a Hulk.