There is no separate NPC type. Residents are characters of the same kind as player characters, with the same body, inventory, vitals, and skills. Residents persist in the world when no player controls them. A resident who dies is permanently dead.
Speech
Any character can talk to any other. Residents have personality traits, and their greetings are drawn from lines associated with those traits. Speech is shown to characters within about 15 metres.
Conversation
Designed and not yet implemented. Conversation has topics. A character can be asked which organizations it belongs to, asked about an organization the asker has heard of, and asked to admit the asker to one it belongs to. What a character has heard of is tracked per character.
Work
Residents can be assigned task lists.