A mod for Potion Craft adding a Hunter faction based on the vanilla Hunter Character. Uses BasicMod (https://github.com/hxpmods/BasicMod/releases).
The code is commented with some of my findings while looking into the NpcSystem, please feel free to use it as a basis for adding your own factions.
This mod does not add quests by itself, but lets you add them via JSON using BasicMod. See https://github.com/hxpmods/MoreRequests for an idea of how to do that/ or to download sample quests.
Also, Factions aren't fully implemented in the base game, chances are something will break here as the game updates but the principles should be the same.