Harvey's blackouts foreshadow his becoming Two-Face, and the symptoms he describes to Dr. Meridian are indicative of dissociative identity, or multiple personality, disorder. In Batman: The Animated Series (1992), prior to the chemical accident that disfigured him, his condition manifested itself in the form of a violent alternate personality named Big Bad Harv.
Dr. Chase Meridian was originally a psychologist/consultant for the police in the movie 'Batman Forever', played by Nicole Kidman. The character was later introduced into the comics in the Herded Limits story line in 'Legends of the Dark Knight', in 2013.