So I’mma be non-helpful, as is my wont, and just talk about myself some more:

What I do (which seems kinda in line with what everyone is saying, but I dunno, y’all are weird) is use the Factions of a given city to say something about that city while giving it a very four-color, easy-to-start-from base.

So like, when I play US Toronto, Night is going to be violent — because their moves are all violence. But violence in Toronto doesn’t mean the same thing it does in American cities. So how does Night handle that? How do wolve and vampires keep a city of 2.8 million at under 40 murders a year?

(They put you in a bag, ship you out of town, and murder you in Kitchener. It’s the only thing Kitchener is good for.)

So, for any city I play in, the four factions are four basic impulses and roughly associated people who cluster around those impulses, in a way that speaks to what makes this city this city.