Chell is the silent protagonist of Portal and the single-player campaign in Portal 2. Very little is known of her past, beyond her possible abandonment at birth and her stubborn will to live. Throughout the series, Chell is antagonized by the AI and facility overseer GLaDOS during her testing courses. Wielding only the Handheld Portal Device, she eventually utilizes this device as a means of avoiding hazards and bypassing various sections of the Facility in order to escape.