You are mildly deranged, but the odd workings of your brain have some benefits.
Benefit: You have a mild case of schizophrenia, and suffer from constant hallucinations that render you unable to determine reality from fantasy (Pathfinder GameMastery Guide, p. 251). You do not have to make a Will save when in stressful situations to avoid becoming confused, but you suffer all other affects of the insanity. Additionally, you are incapable of disbelieving illusions. In return for this, you are immune to all forms of fear (magical or otherwise) as well as all compulsion-based enchantments.
Special: Consult with your GM before taking this feat.
Undefeatable: The Collected Feats Sourcebook, Copyright 2009 – 2010, Louis Porter Jr. Design, Inc. Undefeated, Copyright 2011, Louis Porter Jr. Design, Inc.