Confronter

undefined:

A confronter is a headmate similar to an exposure therapist, in that they expose themselves or others to trauma or triggering topics, whether to try and help them through it, curiosity about how they or others will react, or for fun. This is not always a bad thing, and these headmates usually have the best in mind for their system.

A simple definition is "a headmate who confronts other system members with triggers and trauma."