The non-player characters have their own role in the game. Most are just civilians going about their routine and trying to make the best of their situation. Some have unique roles, such as buying and selling items.
These will appear with a blue dollar sign indicator ($) to aid in their discovery. This is a pretty oppressed country, so their selection can be limited but if you need something right away or want to offload your inventory they are very helpful.
Other key NPCs help progress the story and are often part of quests. These NPCs are indicated by blue exclamation marks (!) on the combat map. You should always make an effort to talk to these people to update quests and find out what is going on in Arulco.
The last special NPCs are people who become motivated by a quest or mission and offer to join your squad. These recruits range from simple freedom fighters to mercs just like your crew. Once they offer to join, you can accept or return later to enlist them.
If you don’t want to continue to use them in your troupe they can be separated into a different squad and left to protect an area.