Melvinborg

Melvinborg retained the arrogance of his younger self and served as a mentor to present day Melvin, though in the worst way possible. He was also more diabolical, causing present Melvin to betray him due to the shock that he left George and Harold from his time to perish. He was also reckless as the present Melvin.

In "The Bizarre Blitzkrieg of the Bothersome Butt-erflies", it is revealed that Melvinborg was a normal person before he was attacked by the Butt-erflies George and Harold sent to that time

Melvinborg begins running the school and replaces the teachers with the Teachertrons after George and Harold's expulsion is repealed due to Mr. Krupp's handwritten rules not being official rules. After George and Harold hack the giant Teachertron, Grace Wain comes and says that Melvin Sneedly Elementary isn't applied to robot teachers yet.

After The M.I.S.F.A.R.T.S convince Krupp to come back in S2 E2, Melvinborg injects the teachers with darts that allow him to control the teachers in a following episode. He accidentally hits Ms. Ribble with too many darts, resulting in the teachers obeying her and not Melvinborg, and she makes the kids make hexagons out of some kind of wax. George and Harold decide to make a comic, but no one seems interested in reading the comic. George and Harold later discover that Melvinborg is trying to control the teachers with the Free-To-Be-Bee 2000. Ms. Ribble appears in queen bee form with the kids and teachers in bee form, revealing that she made the lunch ladies serve honey, which contains bee DNA, to all the kids besides George and Harold. Melvinborg activates a trapdoor, which sends him, Melvin, Krupp and the boys down the sewers. They try to go to downtown Piqua, but it is blocked by honeycomb barriers. Melvinborg and Melvin say that they need to circle back, but George and Harold snap their fingers, turning Mr. Krupp into Captain Underpants and initiating Buzz-O-Rama. It ends with Captain Underpants all puffy due to his bee allergy. At the end of the episode, everyone is turned back into their original selves. Melvinborg and Melvin say to George and Harold that they have the right amount of honey to start over, but two bears chase the Melvins at the end of the episode.

Melvinborg then makes a scoreboard showing Melvin is #1, and he says the class will be about teaching a rat something in the next week. George and Harold return with two clay rats, since their rat (Ratrick) was missing. Just as Melvinborg is about to punish them, everyone smells something horrible, which is Poopacabra. Then, Melvinborg gets thrown against a wall. He doesn't seem to be injured from the impact, with the only damage being done to his phone. This could imply that he's extremely durable.

George and Harold later win the Golden Dumpy from their Trashalanche project, and Melvin falls into #3. Later, Melvinborg makes a final exam, copying traps from George and Harold's comic. Melvin gets powers from Nanobots via an injection given by Melvinborg, but Erica wins. Then the nanobots transfer to Captain Underpants's brain. They fight off the possessed brain cells and get to Nanozero. Once they get to Nanozero and defeat him, Melvinborg suggests to leave George and Harold in Nanozero’s husk. However, Melvin decides that Melvinborg is too cruel and decides to start becoming a better person; therefore, Melvinborg no longer exists.