The World ready!
The easiest way to determine factions would be to simply split them by location, or world history.
Then, the conflict could revolve around gaining or maintaining territory, and that could include groups being pushed out of their original territories and then trying to take them back.
You can also split it by the each of the area’s history, using previous conflicts to shape the factions, i.e. political ones.
The Characters ready!
Build your factions around your characters’ core beliefs.
What do your characters care about? What is their worldview? What about the opposite?
With a focus on the characters, the creation of the factions can become integral to your OC’s story. Will they need to grow out of the faction? Will the faction grow and change as the character does? Will they leave one for another as their story moves forward?
And conversely: what does being in that faction say about the character? What does a monster being in a Hunter’s faction, for example, say about the monster? Are they guilty? Do they doubt their identity, or are they a wolf in Sheep’s clothing waiting to strike?
by Abby Zarakovich