Non-BP is a non-clinical term originally coined by Kreger & Mason in the book Stop Walking on Eggshells. The term has since come into popular usage and describes individuals who are in a consistent, and sometimes significant, relationship with a person exhibiting a Borderline character, aspects of Complex Post-Traumatic Stress Disorder (C-PTSD), or a formally diagnosed Borderline Personality Disorder (BPD). These people can be friends, spouses, lovers, offspring, co-workers, and extended family members, among others.
While Non-BP is a colloquial expression, and not a clinically defined condition or syndrome, the idea parallels that of the roles that people often take on in alcoholic families, or abusive relationships. It is also consistent with the idea of roles described in co-dependent relationships, such as enabler, counter-dependent, and/or agent. Part of the value of this type of informal terminology is that it helps describe the manner in which others potentially behave when in relationship to a person whose social skills are inadequate, in what ever manner that presents.
When talking about the Borderline relationship, the Non-reactive Non-BP is considered to be a person who interacts with the Borderline character, while not being drawn into, or engaging, the chaos of the disorder. The Reactive Non-BP, however, both interacts with the Borderline character, and engages the Borderline behavior. This often throws the person off-center, and promotes a kind of parallel emotional dysregulation within them. The Reactive relationship style breaks down into two distinct sub-styles; transpersonal, or the trans-Borderline, and counter-personal, or the counter-Borderline.