Michael Emerson is the oldest son of divorcée Lucy Emerson. Michael grew up in Phoenix, Arizona with his younger brother Sam, where they lived until the divorce of their parents. Sam and Michael moved with Lucy to the coastal community of Santa Carla, California to live with their Grandpa because they were flat broke.
Though he is a primary character, Michael's personality is kept down to very simple details: he is a quiet, decent, straight teenaged male. His interests are 100% masculine: fitness (he brings a set of weights with him to Santa Carla and is seen working out with them briefly), motorcycles (he is a safe and even slightly timid rider; it seems clear that he has never before done the kind of reckless riding the Lost Boys challenge him to), and girls. Despite this, he's not a macho or arrogant character (when challenged to race by David, he honestly replies "I can't beat your bike"). Overall he is low-key and restrained, and speaks very little: this may be intended to suggest that he is struggling with the emotional effects of his parents' divorce. Unlike his comic book-loving younger brother, Sam, he displays no real interest in anything until he sees Star, whom he then pursues single-mindedly. He displays no flashes of temper until he is tricked into risking his life by David. He shows, however, considerable moral courage as the film develops: although he becomes entangled with the Lost Boys, he shows no attraction to the vampire lifestyle, is frankly frightened by their dangerous stunts, and steadfastly resists a concerted effort to entice him into giving up his humanity.
Besides Star, who he falls in love with on sight, his only close relationship in the film is with his younger brother Sam. It is suggested that they have drawn closer together as a result of their parents' split; they joke together and Michael relies on Sam's help when he begins to suffer the effects of his developing curse. He has a slightly distant relationship with his mother: even before he is infected, he barely communicates with her, which may be typical adolescent moodiness or more fallout from the divorce. His rivalry with David, though it begins as competition for Star, becomes a struggle of wills when it becomes clear that David is not really involved with Star, and that his main interest is corrupting Michael's will and bringing him into the clan. Again, though, Michael never tries talking to David or learning anything about him or the Lost Boys, but simply and stubbornly opposes him (which may be why David finds him interesting).