Ask Probing Questions

Psychological manipulators make requests of you that often make you go out of your way to fulfill them. When they do so, ask questions about the unfairness of the request, to see if the manipulator has enough self-awareness to recognize it in their scheme.

If the manipulator has a degree of self-awareness, he or she will likely withdraw the demand. Truly pathological manipulators (such as a narcissist) will dismiss your questions and insist on getting their way.