Michael is a supporting character in the film. It is explained that he and his older brother John believe that Peter Pan, whom they have learned about from Wendy's stories, is a real person. Thus, they often make-believe that they are Captain Hook and Peter Pan in their nursery games.
At the beginning of the film, Michael and John are playing one of these games, with Michael as Peter Pan. They are having a fake sword fight, as their father comes in looking for his cuff links, as he is getting ready for a party. John realizes that the cuff links were used as buried treasure in their game, but they can't remember where they are and they have lost the treasure map they made. George finds the map, which turns out to have been made out of his shirt front, much to his horror. This upsets George, and he begins scolding all the children for having their heads filled with silly stories. Michael's sister, Wendy protests, and as a result she is told that she will no longer be allowed to stay in the nursery, which upsets Michael. As George goes to leave, he trips over Nana, and thus ties her up outside, which greatly upsets Michael. Michael's mother comforts him as she tucks him in bed. As she goes to leave, he hands over the cuff links and two rings belonging to her.
When Peter Pan appears later, Michael is asleep, but awakens as Peter Pan chases after Tinker Bell. He is allowed to accompany Peter Pan and his siblings to Neverland, and chooses to bring his teddy bear. Nana sees this terrified and tried to stop them, Micheal sees this and spreads some of Tinker Bell's dixie dust at Nana causing her to fly and he calls her to follow, but not realizing that she's been held back by the leash still attached on her collar and is left behind waving at him. In Never Land, he goes off to hunt Indians with John and the Lost Boys. After finding a feather and tomahawk, he plays with them for a bit, but realizes they are about to be ambushed by the Indians. He tries to warn the others, but they don't listen and the entire group is captured by the Indians. They are taken to the Indian Camp, where the Chief reveals that they are being held responsible for the capture of his daughter, Tiger Lily. Though the Chief threatens to burn them at the stake if she is not returned, this punishment is avoided thanks to Peter Pan rescuing the princess from Captain Hook who was the real kidnapper.
Michael parties with the rest of the boys, while Wendy is forced to do chores, and he returns late at night. Wendy, annoyed with Peter Pan, proclaims they will go home the next day, and that they need to sleep. After talking with Michael, it becomes apparent that Michael is starting to forget what home was like, as he at first thinks that Wendy, then Nana was his mother. Wendy is able to remind him who she was, and he agrees to go home, accompanied by the Lost Boys, who wanted to go after hearing about Wendy, Micheal, and John's mother. However, as they go to leave, the entire group is captured by Captain Hook. Captain Hook offers to allow the boys to either join his crew or walk the plank. Micheal almost takes Captain Hook's offer, but is stopped by Wendy. Michael is then forced to watch as Wendy walks the plank. However, Wendy is saved and he is freed thanks to the timely arrival of Peter Pan. A large fight breaks out, and Micheal participates by banging a pirate on the head with his teddy bear, which is revealed to have been stuffed with a cannonball. Afterwards, he returns home on the Pirate Ship, and is asleep by the time his parents return home.
Michael didn't appear in the sequel Return to Never Land and wasn't mentioned by any of the characters, including Wendy. However, he made a couple of shadowy cameos on some starry night clouds that light up by Tinker Bell to begin with (flying with Wendy and John and tagging along with John and the Lost Boys to the Indian campus). His nephew Danny seems to strongly resemble him in appearance and personality.
Michael Darling and the rest of the Darling family appear in the Season 2 episode "Second Star to the Right". He is portrayed by child actor Benjamin Cook. After a boy named Baelfire was welcomed into their family, he and John overhear Baelfire one night warning Wendy to stay away from a shadow that looms outside the window. Wendy ignores his advice and travels to Never Land with the Shadow. She brings bad news on her arrival back; the Shadow wants to take one of her brothers away to Never Land forever. During the next night, Baelfire helps to hide everyone when the Shadow comes. However, Michael doesn't follow the plan and risks being kidnapped by the creature. To avoid the splitting up of a family, Baelfire asks to be taken to Never Land instead.
In "Dark Hollow", John and Michael became employed by Pan after the latter kidnapped Wendy sometime after the events of "Second Star to the Right". Now adults, they arrive to Storybrooke to destroy Pandora's Box, the only thing capable of defeating Pan. While they succeed in capturing the item, they are thwarted by Belle and Ariel in the mines. They reveal Pan is holding Wendy captive in Never Land, so Belle promises she will do what is necessary to save Wendy if they do not destroy the box.
Michael used to be a meetable character in the Disney parks, in the 1980s, usually played by a 6- to 8-year old boy, but child labor laws of the 1990s forced him to be dropped from the face character roster. He is now only mentioned by his sister Wendy. Nevertheless, Michael's likeness can be found in several spots, as well, such as merchandise, as well as having an audio animatronic in the popular attraction, Peter Pan's Flight.
It is possible that the reason why Michael doesn't make a physical appearance in Return to Never Land, is that judging by the setting of the film, it is presumed that Michael (and possibly John) was taking part in World War II.