To clarify terms first, the term “psychopathy” refers to what is called anti-social personality disorder. That is the diagnostic category that refers to individuals who since at least the age of fifteen have shown a clear pattern of both disregard and violation of the rights of others:
Àô Repeatedly engaging in acts that are grounds from arrest
Àô Deceitfulness, conning others, use of false identities for personal profit and pleasure
Àô Lack of future planning
Àô Impulsive behavior
Àô Reckless disregard to the safety of self or others
Àô Failure to sustain consistent work behavior
Àô Failure to honor financial obligations
Àô Lack of remorse for having hurt, deceived or mistreated others
The patient cannot readily be redirected or punished since such individuals feel no guilt or shame.
Also they surround themselves with a combination of others just like them and those who are vulnerable to them.
Once you can document that this is what is occurring (i.e. this is their diagnosis), then you must insure that boundaries are well maintained to protect yourself and others from the inevitable and typically relentless manipulations.