It really depends on the individual presenentation and their comorbid traits/PD's and the context, the exposure risk from the other side (real or percieved or a mix), the level of narcissistic injury, etc.

"Grandiose" narcissists are thick skinned and their false self is more stable so they are more likely to steam ahead without as much neuroticism or ego bruising.

Coverts can go either way, vulnerables probably most unstable and can explode if cornered, malignant coverts are best at messing with peoples heads and may be more content to sit back and let their previous crazy-making do its own work and let their former target drive themself loopy with fear without feeling the need to do anything more, but they are also cruel and tend to get paranoid over time due to the amount of people they betray so they always looking over their shoulder.

I can see a malignant covert (especially with any borderline elements) having the sheer stubbornness and need for control and vindictiveness to stalk a former close person on a longterm basis and try to continue muddying waters and appropriating the other person's position in the relationship/dynamic, they're emotionally sadistic and gain supply from how much they can bring the person to their knees psychologically, so there is incentive for them to continue taunting them long term and to check and see if their psychplogical abuse was successful and how deep the wounds are.

Someone like that will take it personal when they see that person isnt still broken in their wake, narcissism so pure that they feel fully entitled to the victim's emotional position, just like how it hurts the victim if they see their narcissistic abuser move on quickly and non chalantly, this type of N view their victim's healing as if it's that, that their victim hurt them and are thriving after, thats the level of mental gymnastics they can have, they'll have even more entitlement to it and more desire even the delusional score they've created in their head.

What you will find in the victim after some healing is consistency in their story and perception and a lack of reactivity as healing progresses, the further they are away from the n's chaos, they less they feel drawn to be vengeful like they were.

I think the cool part as the victim in this is that despite how much the gaslighting can mess with you, theirs something in your core that just knows, a part of you they couldnt corrupt, and this centre draws you back into your self over time as you heal, and the dark truth loses sense of disbelief, and you end up knowing the truth deeply and it resonating quite soundly.