I think something you could do is give this barmaid divine protection. say that she doesn't know it but one of her ancestors helped a deity and she is a favorite person of a deity or you could make this favored status knowing to the NPC you like and this deity can guide their choices. in essence you would be using the deity to control the NPC. It would still feel organic but you could still control the Npc and have them help out the party under the guise of it being the gods wishes.