Get Amnesia

Intro
The "Amnesia! Huh? What?" plot is where someone loses their memories, likely to a violent head-on collision, and either regress to a blank slate or act like a different person. Others around them might take advantage of a blank slate amnesiac and lie to them as they don't know better, and a new personality amnesiac could take on an attitude that those around them don't like, persuading them to fix the amnesiac's memory problem.