|Effects||Companions and allies are highlighted in green when in combat|
Characters that are part of your team are high-lighted green in combat instead of red, if you have this Perk. Red high-lighted characters may still be non-hostile towards you.
”— Fallout description
Friendly Foe is a perk in Fallout.
Allies (party members and caravan guards) are highlighted with a green outline in combat. This perk is utterly useless and should be avoided like the plague, as only 7 perk slots are available in Fallout. Fallout 2 and Fallout Tactics implement it as a regular gameplay option instead.