This is a very interesting question but the answer is very complicated, so I hope to clarify some general issues and perhaps be able to divide the question into more specific questions.
In the first place it would be advisable to differentiate between a markedly narcissistic personality and what might well be considered a personality disorder. From this differentiation we could focus more on the subject of the negotiation or therapy.
Cooperative negotiation. (It is not so much an explicit negotiation, can be considered a technique that pursues the influence) It is something that must be studied for a long time, and also practice through role-playing. It is important to take into account our own negotiation profile. This is a complicated topic because often the key is to lead the person to a negotiation or agreement perspective and this contrasts with posing clear positions that are not negotiable.
I not negociate I negociate
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stance point, here and now
This is usually worked in the manuals under the terms negotiation profile, negotiation style. It can be consulted in Morton's books.
Personality disorder and violence (explicitly clinical). There are different professional specialization courses about: different personality disorders, for specific areas (schools, family, psychiatric context), focused on types of situations (bad news communication, psychology in emergencies, first aid psychological, and how to intervene in situations of violence.
You can also find more information on the internet about reinforcement, learning, Behaviorism and behavior modification.
In short there is no formula or conditions that warrant that providing feedback to a narcissistic person does not lead to a violent response, this is something that professionals must study for a long time, I think that the most appropriate is a professional to handle such situations.
Sources about Histrionic Personality Disorder:
- American Psychiatric Association. Diagnostic and statistical manual of mental disorders (DSM-5). pg 667 and next.
Sources of cooperative negotiation:
Morton Deutsch and Peter Coleman. (2000). The handbook of conflict resolution: theory and practice. San Francisco: Jossey-Bass Publishers.
Taylor, A. (2002). The Handbook of family dispute resolution: Mediation theory and practice. San Francisco: Jossey-Bass Publishers.
Lax, D. and Sebenius, J. K. (1986). The manager as negotiator: Bargaining for cooperation and competitive gain. New York: The Free Press.
Sources about Conflict in social psychology (conflict and violence are recurrent themes in social psychology manuals, so many manuals could be cited):
- Forgas, J. P., Kruglanski, A. W. and Williams, K. D. (2011). The psychology of social conflict and aggression. New York: Psychology press.