In the original Mirage comics Michelangelo was described as a hot head almost as bad as his elder brother Raphael. It was his one shot comic that presented him with many of the characteristics that the the character is known for including his sense of fun and care free attitude.
Set at Christmas the comic has Michelangelo heavily disguised walking though central park and sledding with some children. He comes across a stray cat which he adopts and calls Klunk. Checking out a toy store and playing with the latest toys he follows Klunk to the back of the store to find a group of robbers stealing toys meant for an orphanage. After stopping the robbers, he along with his brothers, Klunk and April deliver the toys to the orphanage themselves.
During the turtles exile in Northampton Michelangelo's behavior worried April. Were once he was the one that always be counted on to find a fun in anything he would hardly joke anymore bar some light hearted jibes with Raphael and Casey Jones. He would spend most of his day in the barn constantly training and taking his aggression out on a punching bag. One day he loses control and lashes out at his surroundings continually punching the wall until he bursts through it eventually giving up and leaning on the wall despondently. After Splinter puts him and his brothers through intense training the end of the story strongly suggests that he has returned to usual self.
When Casey Jones introduced the turtles to his baby daughter Shadow the two of them had an instant bond with him teaching her to play video games and her nicknaming him "Rooish". When the turtles decided to get their own places Michelangelo chose to stay in April's apartment so he could be close to Shadow.
Splinter has at times expressed concern that Michelangelo was the only one of his brothers not to follow the path of the warrior and that he must leave his pureness behind. When Klunk was hit by a car he took his pet to a witch doctor who said that an equal life to be sacrificed to save Klunk. Michelangelo found a mangy alley cat who no one cared for but in the end could not use it as a sacrifice and allowed Klunk to die. Returning to Splinter Michelangelo admitted that his sensei was, right that he didn't follow the path of the warrior and as a result someone he cared about died. Splinter corrects his son saying "I am not perfect, my son. Perhaps you, who walks two paths, has something to teach me"
Several months after the arrival of the Utroms on Earth Michelangelo was given a job as a tour guide for visiting aliens. His first assignment was Seri, an alien princess of a saurian race. First taking to the Natural History Museum he convinced her to ditch her body guards and too her on a road trip ending up in Ogunquit, Maine.
At first the relationship between Michelangelo and Seri was volatile due to her royal upbringing constantly shifting between warm and affectionate to that of disgust, when Michelangelo saves her her from drowning the two of the return to the sea emerging with eggs that contain their children. Not long after Seri's Styracodon bodyguards came and beat Michelangelo into a coma and smuggled him off the planet.
Put in a rough alien prison the only person that would talk to him was a blind Triceraton who advised him to keep his head down. When in the prison yard he saw Seri and jumped the wall to reach her, however when the guards pounded him she acted as if she did not recognize him. With the help of his Triceraton ally he managed another escape attempt with the dinosaur alien sacrificing his life to save him leaving the turtle to wonder why he would do such a thing.
Once out of the prison he was picked up by Triceraton ship was had come to extract Michelagelo's ally. They healed the wounds he's incurred at the hands of the Styracodon's. Michelangeo was shocked to learn that far from regarding him as a foe their defeat at the hands of the turtles years prior had led the Triceratons admiring them. Arriving at the Triceraton Homeworlds Michelangelo's had an appointment with the Prime Leaders who explained that attempts at diplomacy had failed and they were declaring war on the Stycadorons. Michelangelo eager for revenge joined with the Triceraton forces.
In August 2011, IDW partnered with Nickelodeon will launch a new ongoing series Teenage Mutant Ninja Turtles written by creator Kevin Eastman. It will be co-written by Tom Waltz with Dan Duncan supplying the art. Instead of wearing his regular orange bandana, Michaelangelo will be wearing the classic red.