Factions represent third party entities in the battle between the PC and the Villains. As such they represent another avenue for the supplies and intel for both sides. Factions generally fall under three categories: Government, Populace and Business. Take note that the category of the faction has nothing to do with the legality of their actions, a local mafia gang is just as much a Populace faction as a homeless shelter.
Government factions obviously represent government interests. As such it is better for these to be use for individual agencies, unless your game focuses on a more world traveling affair.
CIA, FBI, Chinese Secret Police, IRS
Populace factions are specific movements with the civilians.
Local political parties, High School Paranormal Club
Business is a catch all term for any sort of for profit organization that has influence
Genetic Engineering Company, Quirky Startup
Each notable faction is ranked by Tier—a measure of wealth, influence, and scale. At the highest level are the Tier V and VI factions, the true powers of the city. Your crew begins at Tier 0.
You’ll use your Tier rating to roll dice when you acquire an asset, as well as for any fortune roll for which your crew’s overall power level and influence is the primary trait. Most importantly, your Tier determines the quality level of your items as well as the quality and scale of the gangs your crew employs—and thereby what size of enemy you can expect to handle.