Q. Is it even possible for a person to have both BPD and NPD? Some clarification on ways the two relate to each other would be nice.

A. Having both borderline and narcissistic personality disorder is fairly common. All the personality disorders frequently co-occur, and it is not unusual to have 4 or more personality disorder diagnoses at a time. Both BPD and NPD when they co-occur should be viewed as part of the same biological illness.