I think non-player Characters should be able to have cards too. Both because it will help define their personalities more clearly (in ways that aren't visible to the players!) and because then they could more actively assist or oppose actions in a scene. Helpful-NPC can provide a card to help overcome a challenge, while Antagonist-NPC can do things that would detract from their efforts (perhaps subtracting from their total, or aiming towards their own goal).