A PC subpath is a organiztion based around first a base class (Warrior, Rogue, Mage, or Poet) and then a distinct RP (Roleplay) system. They are further characterized by the fact that they are run and controlled by other players much like clans, who handle teaching and inducting new members, as well as community events and various other things. This is the main difference between a PC and an NPC subpath.
This is the list of all current PC Subpaths:
Warrior: Barbarian, Chongun, Do