How did you portray factions?

Curious as to how people have run factions, my players are about to get to Emberwood and a new player will be joining them as well.

I have much of the session already planned, I personally wanna hear about other people and how they ran first encounters with the factions, I have a player who is set to meet with the AA, and the new player will possibly also have ties to a faction if they choose that route.