Rage
From NEStalgia
Rage is one of four resource systems used by companions with the others being MP, Will, and HP. Rage is identical in function to the Credit system used by merchants and is gathered by taking damage, inflicting damage via any attack that has no Rage cost (i.e., normal attacks, non-ability critical hits, ChocoComa, Petrify, etc), and at the start of a new round.
Companions that have access to the Beating and/or Hostile milestones can increase the amount of rage they gain when taking any type of damage (Beating) or inflicting 'free' damage (Hostile).