He was friends with Wendy Harris, and was on good terms with Mal Duncan as well. Despite almost bumping into him on the first day of school, he became friends with Conner Kent. Marvin was not the smartest student in the class, and somewhat of a slacker.
During the Team's "alien invasion" training scenario, Marvin, along with the rest of the students and faculty hid below the school's underground bunker and watched the Team's speech about how they would win and build from what they've lost, after the Justice League had been killed.
Marvin planned what he thought was the best Halloween prank ever. He made sure everyone got text messages about an impending Martian invasion, and at the height of the party, cut the power to the gymnasium. From behind the bleachers, he spoke on the PA system pretending to be a homeland security agent, urging them all to stay indoors.
Conner Kent saw through the plan, and with Megan and Wally, he exposed him by pretending there was an actual Martian invasion. It scared Marvin so much that he stormed into the gymnasium and confessed the prank.
Wendy Harris and Marvin White are based on Wendy and Marvin, the two sidekicks from the Super Friends cartoon. Their designs were updated for Young Justice by Jerome Moore. Moore felt that Marvin always resembled Shaggy from Scooby-Doo, so elements of that look were preserved in Marvin's Young Justice design.
Background in other media
Wendy and Marvin originally appeared as the two sidekicks from the Super Friends cartoon, along with their pet "Wonder Dog".
In 2006, Wendy and Marvin were introduced into the mainstream DC Comics continuity as twin siblings and supporting cast members of the Teen Titans. While not super-heroes, they worked as tech support and caretakers for the Titans Tower. During a controversial storyline, a demonic version of Wonder Dog attacked and killed Marvin, and left Wendy crippled from the waist down. It was also revealed that Wendy and Marvin are the children of the super-villain computer hacker, The Calculator. Furious that his son was killed under the watch of the Teen Titans, Calculator kidnapped the Teen Titans member Kid Eternity and attempted to force him to resurrect his son.