Michael's "sort of sister" as her grandfather is Michael's human donor. Charles Dupree (Laurie's grandfather) gave some of his DNA to help create Michael's human body. Laurie is first seen when Isabel Evans has a premonition of Laurie being buried alive by Grant Sanders and saves her. Laurie has been in a mental hospital since her grandfather's death because she believes that she is being hunted by aliens. Michael and Maria follow her untill they find her in a crashed ambulance and save her life. She is at first very afraid of Michael because of his startling resemblance to her dead grandfather.
After Michael and Maria bring Laurie home to a huge mansion and a very nasty uncle and aunt, they learn that Laurie's uncle and aunt have been paying doctors to keep her in the hospital so that they could have the house and furniture that really belonged to Laurie. Thanks to Michael and Maria, Laurie got her house back and was free. It is thought that Laurie has some kind of psychic power because she was able to interrupt Isabel's dreamwalk and plead for help. This may also be the reason why the blue crystals were after her.