Some TMNT stuff was always meant for grownups.
In the Mirage comics, Michelangelo did not prank, joke or gag as much as he did in later adaptations of the series. In this version, however, Mikey was still the happiest and most open Turtle, which frequently brought him problems. In the original comic books, Michelangelo was initially depicted as fun-loving, carefree, and, while not as aggressive as Raphael, always ready to fight. He was much more seriously natured than other incarnations such as his film self, which was portrayed as a permanently "cool"-talking youngster. It was Michelangelo's one-shot in this series that fleshed out most of the traits that have become synonymous with the character, such as his playfulness, empathy, and easygoing nature. In the one-shot story, Michelangelo adopts a small stray orphaned cat (which he lovingly names Klunk) and also stops thieves from stealing toys meant for orphaned children.
After their defeat at the hands of the Foot Clan the Turtles, Splinter, April, and Casey retreat to a farm house in Northampton, Massachusetts which used to belong to Casey's grandmother. While there, April is worried to note that Michelangelo is not himself. He spends his days in the barn taking out his aggression on a punching bag. A scene shows him lashing out at his surroundings and repeatedly punching the wall of the barn until it breaks, then collapsing on it despondently, anger spent. The end of the story implies that Michelangelo's sorrow and frustration have been resolved, as subsequent issues reunite Michelangelo with his more relaxed, optimistic personality.
It is during this time at the farm we learn that Michelangelo also has an interest in comic books, specifically ones involving superheroes such as "The Justice Force" (comic book heroes based on The Justice League and The Fantastic Four). He also found solace in writing fiction and produced a story depicting himself a ronin in Feudal Japan. (TMNT Volume 1 # 17).
In the story arc "City at War", Michelangelo instantly bonds with Casey Jones' adopted daughter Shadow, who nicknames him "Rooish". In the second volume, the Turtles decide to try to live apart from one another. Michelangelo, being the social creature that he is, moves in with April and Casey so that he can be close to Shadow. Throughout the first two volumes, Michelangelo seemed to act as peacemaker of the team. These stories also laid the foundations which demonstrated his closeness with Donatello; their laid back natures separating them from the more contentious Leonardo and Raphael.
In Volume 4, Michelangelo gets a job as a tour guide showing alien visitors around Earth. His first (and only) tourist is the Regenta (or "princess") Seri of the Styracodon race. Michelangelo convinced Seri to sneak away from her bodyguards so that he could take her on a tour of the northwest coast of the U.S. During their time together, Mike and Seri eventually became intimate, and Seri soon laid a clutch of eggs strongly implied to be the children of their mating. Soon after, Seri's bodyguards returned, overpowered and detained Mike, carted up the eggs, and secretly smuggled them off the planet to their home world. Mike found himself in an extrajudicial prison where he was starved and tortured for weeks. With the help of his Triceraton cell mate Azokk, he managed to escape, though Azokk died in the process. Michelangelo was then rescued by a group of Triceratons who had come to rescue Azokk, and became friends with their Captain T'Zirk. Mike decided to join forces with the Triceratons, becoming one of their commandos, and helping train them to fight the way the turtles fight. Thereafter, Michelangelo's story took an even darker turn, with him participating in acts of genocide in the Triceratons' war against the Styracodons, and bitterly seeking revenge against Seri for the events that led him there. All the while, none of Michelangelo's family or friends on Earth appear to be aware of anything that has happened to him since he took off with Seri to New England, and he is still a missing person.
Michelangelo was not given an especially large role in Volumes 1 and 2, did little to advance the plot, and was often not portrayed as an especially skilled fighter. His relatively small role was probably due to the need to establish Leonardo's role as "leader" along with the fact that Donatello was Peter Laird's favorite Turtle, and Raphael was Kevin Eastman's favorite. By contrast, among the characters in Volume 4, Michelangelo experienced some of the most complex character development, undergoing harrowing experiences that have hardened and embittered him, in stark contrast with his once irrepressibly carefree and fun-loving personality.
This Mikey briefly appears in Trans-Dimensional Turtles.
- Kevin Eastman developed the personality of him based on his good friend Steve Lavigne.