An NPC Subpath is much like a PC Subpath in that it is based around one of the main four classes (Warrior, Rogue, Mage, and Poet). But unlike the PC subpaths entry into the path is done through an NPC quest, and the paths have for the most part no unifying RP, but anyone who is a member of the appropriate main class can join as a result.
The NPC Subpaths are as follows
Warrior: Chung Ryong
Rogue: Baehko
Mage: Ju Jak
Poet: Hyun Moo