Hello Tsubo! Essentially characters who are dropped and then come back onto the Retrospec network will remember everything from their time in-game (both game events and any regained memories they recalled) but they will not remember any of the huge game events from the months prior! They would maybe recall things were "different", but like most NPCs this wouldn't be a cause for concern. For example, they may remember that there was a period of time they didn't see certain members of the city but there would be no explanation as to why, or they would recall reacting to certain things like powers/appearances once upon a time. They otherwise would remember just going about their normal, AU life as if nothing happened.

TL;DR they won't remember the game events themselves or what's happened in the city involving Retrospec since they went NPC status even when they regain memories of Retrospec.

We hope this makes sense and we hope this helps!