You only fight to defend yourself or those in your care, using only as much force as necessary (no pre-emptive strikes allowed!). You must do your best to discourage others from starting fights.
You are psychologically unprepared to kill people. Whenever you make a deadly attack (e.g., with a knife or a gun) against an obvious person whose face is visible to you, you are at -4 to hit and may not Aim. If you cannot see the foe’s face (due to a mask, darkness, or distance, or because you attacked from behind), the penalty is only -2, save in close combat. You have no penalty to attack a vehicle (even an occupied one), an opponent you do not believe is a person (including things with Horrific or Monstrous appearance), or a target you can’t actually see (e.g., a set of map coordinates or a blip on a radar screen). If you kill a recognizable person, the effect on you is the same as for Pacifism: Cannot Kill. You have no problem with your allies killing; you may even supply ammo, loaded weapons, and encouragement! You just can’t do the killing yourself.