Here's a start:

IF
CharacterAttackedByCharacter(_Atackee,_Player)
AND
DB_Citizen(_Atackee)
THEN
CharacterSetTemporaryHostileRelation(_Atackee,_Player);



Any global character added to DB_Citizen will fight back when attacked.

Getting people to recognize theft is going to be more tricky, but I need to work on that anyhow.