Star was turned into a half-vampire by David at some point in the past. She developed maternal feelings for Laddie, a young boy who was also half-vampire. David then used her to lure young men to his hideout to turn into vampires, namely Michael.
MichaelMichael was instantly attracted to Star. Even when he saw her straddling David's bike, he still tried chatting her up. Star seemed to care for Michael, enough to warn him that the wine David offered him was actually vampire blood. When Michael noticed that he was turning into a vampire, he confronted Star, not knowing that David had instructed her to distract Michael by sleeping with him.
Star warns Michael that David plans to make both them and Laddie full-fledged vampires by having them kill. Michael, his borther Sam and two local teenagers, Edgar and Allen Frog, keep her safe in his house while they fight David and his gang, eventually managing to kill all of them. Star, Michael and Laddie are turned back to humans when the vampire leader is killed. It is implied in the third Lost Boys movie that she and Michael got married sometime after the events of the first film.