Anything that builds up a narcissist's ego, makes the N feel superior, or makes the narcissist feel powerful, feared, or significant will be supply to the narcissist, whether POSITIVE OR NEGATIVE, and that's important, because many people think that after the break up, contact with the narcissist in which they display clear hostility will discourage the narcissist and make them go away. It won't, because it's also supply. What makes the N go away is DEPRIVING THE N OF SUPPLY by refusing to give any response of any kind, called the gray rock method, that is, giving the same response as a gray rock.
But, that's not the two types of supply you need to know about. The two types are PRIMARY SUPPLY and SECONDARY SUPPLY, and after this you will be able to easily identify them, and knowing this makes the narcissist's behavior more understandable.
Primary supply means being adored, adulation, being looked up to, being popular (or famous), or negatively, being feared or being notorious. You notice that some people commit horrible crimes so they will be known and hated, and be notorious....but they are not anonymous and irrelevant....that's also primary supply.
The narcissist may cultivate a reputation for sexual conquests, or for having friends in high places (supposedly), or military or personal exploits, or for extraordinary spirituality and religiousness. In a negative sense, they may use lies, and fear of physical abuse, or emotional abuse, or play on your fear of them spreading terrible rumors and other slander about you. Supply, and power and control go hand in hand.
Now, the other type of supply is called SECONDARY SUPPLY, which is derived from things like being thought a good family man and leading a “normal” life (as far as people know, that is), having an admirable partner, attending religious services, being financially secure, and the like. Secondary supply can also be gotten by the success of the narcissist's partner and the N's association with them.
Whatever would be a status symbol in the narcissist's group of friends and would be thought of as success IN THAT GROUP is secondary supply. Secondary supply is about the general appearance that the narcissist's life gives to the narcissist's friends and family, and the world generally.
Now you can understand why the narcissist chose you. You are part of the narcissist's plan to get secondary supply and appear normal, or successful to those the narcissist is trying to impress. You were chosen because you are normal, kind, loving, a good parent, responsible, so your being with the narcissist means that the narcissist MUST be a good person and WORTHY of your love, which the N is NOT.
You were chosen for your VIRTUES in order to cover the narcissist's vices. That's right...YOU WERE COVER for his façade, his fake self, and when you no longer serve that purpose, or someone else will serve the purpose better, you will be discarded. If the new supply fails to serve this purpose, then you will be hoovered (trying to draw you back into the N's life) and the N will resume the relationship for a while so the N is not without secondary supply , but hoovering also has other purposes as well.
Keep this in mind...to the narcissist, you serve a purpose, just like an appliance...you have utility for a practical purpose, which is supply. When someone tires of an appliance, or they think another appliance works better, they discard the old appliance in favor of a newer model. It's hard to come to the reality that this is how the narcissist actually viewed you, despite the N claiming that they loved you. They didn't.
THEY LOVED WHAT YOU COULD DO FOR THEM, and it was NEVER more than that.
That's sad, but understanding that to the narcissist, your daily life was nothing more than secondary supply means that when the N hoovers, you see the N is a totally different and more realistic way. The fog lifts, and you see the truth....and so, you can move on.