Traveler

Occasionally, one or more members of a friendly faction will arrive, just passing through. They'll enter at one edge of the map and proceed across the map. They'll exit the map upon reaching another edge.

A drafted colonist can be directed to capture (arrest) one of the travelers. However, once the arresting colonist reaches the target, that entire faction will immediately turn extremely hostile, dropping to around -75 Goodwill.<--! Witnessed a shift from +4 to -76 with a "Gentle Tribe" faction, but no idea of that's the default or variable--> This shift includes any other members of the same Faction currently there.