Back to La-la Land

Relationships with narcissists peter out slowly and tortuously. Narcissists do not provide closure. They stalk. They cajole, beg, promise, persuade, and, ultimately, succeed in doing the impossible yet again: sweep you off your feet, though you know better than to succumb to their spurious and superficial charms.
So, you go back to your "relationship" and hope for a better ending. You walk on eggshells. You become the epitome of submissiveness, a perfect Source of Narcissistic Supply, the ideal mate or spouse or partner or colleague. You keep your fingers crossed.
But how does the narcissist react to the resurrection of the bond?
It depends on whether you have re-entered the liaison from a position or strength – or of vulnerability and weakness.
The narcissist casts all interactions with other people in terms of conflicts or competitions to be won. He does not regard you as a partner – but as an adversary to be subjugated and defeated. Thus, as far as he is concerned, your return to the fold is a triumph, proof of his superiority and irresistibility.
If he perceives you as autonomous, dangerously independent, and capable of bailing out and abandoning him – the narcissist acts the part of the sensitive, loving, compassionate, and empathic counterpart. Narcissists respect strength, they are awed by it. As long as you maintain a "no nonsense" attitude, placing the narcissist on probation, he is likely to behave himself.
If, on the other hand, you have resumed contact because you have capitulated to his threats or because you are manifestly dependent on him financially or emotionally – the narcissist will pounce on your frailty and exploit your fragility to the maximum. Following a perfunctory honeymoon, he will immediately seek to control and abuse you.
In both cases, the narcissist's thespian reserves are exhausted and his true nature and feelings emerge. The facade crumbles and beneath it lurks the same old heartless falsity that is the narcissist. His gleeful smugness at having bent you to his wishes and rules, his all-consuming sense of entitlement, his sexual depravity, his aggression, pathological envy, and rage – all erupt uncontrollably.
The prognosis for the renewed affair is far worse if it follows a lengthy separation in which you have made a life for yourself with your own interests, pursuits, set of friends, needs, wishes, plans, and obligations, independent of your narcissistic ex and unrelated to him.
The narcissist cannot countenance your separateness. To him, you are a mere instrument of gratification or an extension of his bloated False Self. He resents your pecuniary wherewithal, is insanely jealous of your friends, refuses to accept your preferences or compromise his own, in envious and dismissive of your accomplishments.
Ultimately, the very fact that you have survived without his constant presence seems to deny him his much-needed Narcissistic Supply. He rides the inevitable cycle of idealisation and devaluation. He berates you, humiliates you publicly, threatens you, destabilises you by behaving unpredictably, fosters ambient abuse, and uses others to intimidate and humble you ("abuse by proxy").
You are then faced with a tough choice:
To leave again and give up all the emotional and financial investments that went into your attempt to resurrect the relationship – or to go on trying, subject to daily abuse and worse?
It is a well-known landscape. You have been here before. But this familiarity doesn't make it less nightmarish.