Board Thread:Episode Discussion/@comment-14138255-20170122163519/@comment-14138255-20170122171032

From the looks of things, Aura seems to either be unlocked manually or automatically after certain stimuli like fear, pain, or another person's Aura. It unlocking through stimuli makes sense on an evolutionary level, being a defense mechanism for a race that has been acting as prey to the dominant life form on the planet before Dust was discovered.