Hoovering is named after the vacuum cleaner brand, and the metaphor is apt: it is the narcissist's attempt to suck you back in after a period of separation. It can happen weeks, months, or even years after you have left or been discarded, and it almost always arrives at a moment when you are beginning to heal. The timing is not coincidental. Narcissists are remarkably attuned to when their former sources of supply are becoming less accessible to them, and they return precisely when they sense that window closing. The hoover attempt takes many forms. Sometimes it is a seemingly innocent text checking in. Sometimes it is a dramatic declaration of change and remorse. Sometimes it is the deployment of a mutual contact who just wants you to know how much the narcissist has been struggling. Sometimes it is a manufactured crisis that requires your involvement. What all of these have in common is that they are designed to re-establish contact, and re-establishing contact is the first step in re-establishing control.
The narcissist who hoovers has not changed. This is the single most important thing to hold onto when a hoover arrives and the old feelings surge back with it. The remorse is real in the moment, in the sense that the narcissist genuinely wants you back, but wanting you back is not the same as being capable of treating you differently. The pattern that existed before your separation will exist again if you return, often more intensely, because the narcissist now has the additional leverage of knowing that you left and came back. If you receive a hoover attempt, the most protective response is no response. If complete non-response is not possible, a single brief, neutral acknowledgment that closes the conversation rather than opens it is the next best option. You do not owe them an explanation for your continued distance. You do not owe them the closure conversation they are requesting. You owe yourself the life you have been building since they left it.