Narcissistic mothers are doting, and loving and caring, they are the image of perfection, until you do, say, or think something they don't want you to do, think or say.
A narcs mother's love is highly conditional and her approval is immediately withdrawn when things don't go her way. Not the usual disapproval that elders generally have for the younger generation, not the cultural stubbornness usually observed in traditional and immigrant families. A narcs disapproval is more asinine, more intentional, more calculated.
They train you from childhood to believe that they're disapproval is the end of your world. You feel physically sick thinking of them being upset. Not your having an opinion of your own, it is the thought of their reaction and the yelling, stonewalling or abandonment that happens when they realize you've dared to take them on.
This creates rivalry between you and your sibling(s) if any. Disagreement with a narc creates an uncomfortably tense environment, which you then grow to dislike, thus making you afraid to have an identity outside the narcissist and leaves you helpless to their dominance and control.