Michael's parents died when he was little, forcing him to go live with his uncle, Cobra. Cobra taught Michael stealth and computer hacking as part of a CIA project to train young recruits as soldiers.
After two years of training, Michael and Cobra travelled to Kauai for the hunt for Stitch.
When Michael was eleven, he was tracking Kristy, despite his superiors' warnings to abandon the assignment, and was brutally beaten by Kristy's thugs and left for dead. Michael was found by Cobra, and spent a month recovering in hospital, and left the CIA.
Once Michael was released from hospital, be spent six months with nothing to do but study Stitch's DNA, and then returned to Kauai. There, he helped Jumba create Experiments 627 and 628. However, just as Jumba and Michael finished 628, Cobra forced Michael to move out of Hawaii; the CIA wanted to bring Michael back in, which neither Cobra nor Michael wanted, so Jumba and Cobra fashioned Michael a new name, Skipper, and moved him to Germany.
The CIA gave up the search after 1-2 months and when he was fourteen, Skipper was able to move back to the US mainland, but still had to keep his new name. With little money, Skipper paid the stock market and gambled illegally at casinos in Las Vegas.
Two years later, when Cobra informed Skipper that Hamsterviel had escaped prison, he decided to hack a satellite to check on 628, and saw Hamsterviel steal 628's pod from the garbage. Skipper then moved back to Kauai to inform Jumba.
Shortly after Skipper moved back, Lilo and Stitch invited Skipper to the Pelekai household for dinner, where he explained what had happened to Jumba, Lilo and Stitch. Later, Cobra arrived to inform them that Hamsterviel was indeed on Kauai somewhere, and Lilo, Stitch and Skipper left on a manhunt for Hamsterviel's hideout. When Lilo and Skipper were alone, Skipper questioned Lilo about her feelings for Stitch, and admitted that he himself liked Angel.
The manhunt ended in disaster when, while Stitch had left to visit Angel, Lilo and Skipper were attacked by 628, infected, and rendered unconscious. When Stitch and Angel found what had happened, they took Lilo and Skipper back to the ship until they woke up.
After Skipper recovered and awoke from the attack, Jumba explained what he had found out about 628; due to the attack on him and Lilo, they would both inevitably transform into experiments the following night.
Lilo and Skipper spent the five hours they had left as humans surfing with David, before returning home for their transformation. Jumba used Drowsy to put Lilo and Skipper to sleep (so they would not be conscious to feel the pain of their transformation), then set up a system to wake the two up the next morning. Minutes later, Lilo and Skipper excruciatingly transformed into genetic experiments in their sleep, and after taking DNA samples from them, Jumba left them to sleep.
Lilo and Skipper awoke the next morning, and, after seeing the full extent of their transformation in a mirror, went downstairs to greet the others. Lilo and Skipper had breakfast, and once they were finished, Jumba took them to his ship to test any new powers they had. While Angel was testing Skipper's karate, the two found that they were becoming increasingly attracted to one another.
After they finished, Stitch and Angel decided to go for a walk, to Lilo's anger. Lilo and Skipper then began arguing about how they felt for Stitch and Angel, and made a deal: when one of them told their love interest how they felt, the other would have to do the same.
That night, due to a feeling that he was being watched, Skipper searched the house, and discovered Hamsterviel and his camouflaged ship. He contacted Reuben, telling him and Gantu to come to Earth tomorrow, then devised a plan with Lilo, Stitch and Angel to launch an attack on the ship the next day. They explained what had happened to Lilo and Skipper, before launching their attack on Hamsterviel's bunker that night. They split into two teams, with Skipper's team going in the front door, and making their way through the bunker to the control room, where they met up with the other team.
However, once they reached there, they were confronted by Hamsterviel and his new experiment, Smasher, who easily shrugged off the experiments' attacks. Eventually, as the experiments began to tire and their attacks became weaker, Smasher attempted to kill Stitch by impaling him with a projectile bone, allowing Lilo's dark side (Athena) to take control.
After telekinetically crushing Smasher into oblivion, Lilo/Athena attempted to telekinetically choke Angel, sending Skipper into a rage. Skipper's anger and rage towards Lilo/Athena for hurting Angel allowed Apollo (a mental manifestation of Skipper's dark side, created by his transformation into an experiment) to temporarily take control and attack. Lilo/Athena and Skipper/Apollo fought, with Lilo/Athena telekinetically blocking Skipper/Apollo's attacks.
Lilo eventually retook control of herself from Athena, but Skipper/Apollo, consumed in rage, did not stop his relentless attacks. Angel tried to calm Skipper/Apollo down, but the latter, in his rage, did not recognise her and attacked her. Just when Skipper/Apollo was about to finish Angel off, she wiped blood from a wound inflicted by Skipper/Apollo across his face. This allowed Skipper to retake control over himself from Apollo. Seeing what Apollo had done, Skipper broke down, blaming himself.
However, just then, Hamsterviel fled the bunker and revealed a bomb that would destroy the bunker and kill everyone in it if they didn't stop it. Skipper determined that the bomb was touch-activated and sacrificed himself to stop it. But just before the bomb lifted off, Skipper confessed his love to Angel, and Angel confessed hers to him.
However, after the bomb took off, upon hearing Angel declare that she loved him, Skipper was torn between letting himself die so that Apollo could not hurt Angel, and surviving so that he could be there for Angel. He ultimately decided the latter, and placed his plasma pistol in the bomb before jumping off and landing on the ground. However, when the bomb exploded, Skipper's back was badly burnt and damaged, leaving him severely wounded and he spent an entre day making his way across the island to the Pelekai household.
Skipper resembles a purple cross between Stitch and Reuben (625): he has dark purple back markings, and white-pink front markings. He also has four arms, three spines on his back, and a Reuben-like tuft of three antennae.
Skipper has increased intelligence and mental capacity, and can comprehend strategies in the blink of an eye. He can also scale walls, and has night and heat vision, and great karate skills.