This is just my thoughts. If we are to become the warriors of darkness, then what would become of Thancred, Y'shtola, and Urianger? If we had to become the opposite of the warrior of light, maybe we are looking at their opposites?

Thancred used to be I guess a rogue(quiet and sneaky). but now a loud tank?

y'shtola used to be a healing class (so it seemed) but now is what appears to be a black mage but clearly is a new job. I'm guessing its one of the two
  • Magus - I am leaning towards this as black mage was needed before acquiring this in final fantasy 4.
  • Sage - Not so much as this job uses both White and Black mage separately. Remember Tellah?

Urianger - Was this guy ever on the light side? I remember the mess he got us into with that other warrior of darkness. This guy is darkness certified!