Personal assistant to Dr. Ira Graves, who cared for the brilliant scientist during his terminal illness while working in isolation on a planet referred to as Gravesworld. Kareen lived on Gravesworld since her father died when she was quite young. Graves taught her most of what she knew about the universe, including how to identify nonhuman species (although upon meeting Worf she was confused about the difference between Klingons and Romulans). Kareen was a beautiful young woman, and there was a mutual attraction between her and Graves, but their age difference prevented a romantic relationship from forming.

In 2365, when Graves' health began to fail rapidly, Kareen, without Graves' approval, sent a distress call urgently requesting medical aid, to which the Enterprise-D responded. When Graves died, Kareen boarded the Enterprise so she could be taken to the nearest starbase and start a new life. During that journey, Graves' consciousness was occupying Data's android body, and he became extremely jealous when he observed the attention that Captain Picard was bestowing upon the object of his affection. Graves later approached Kareen and revealed himself, declaring his love for her, and vowing to create an android body for her so they can live together forever. But she was repulsed by this idea. Feeling her rejection, he inadvertently injured her by holding her hand too tightly. Later, Kareen discovered that Graves had voluntarily left Data's body and deposited his consciousness in the ship's computer, an act of conscience which restored her respect for him. Kareen went to live on Starbase 6, with hopes of a bright future.