The PCs come across a town with a strange curse: Every morning, those who have grown up here wake up with the memories of someone else. They do not find this strange and have no idea it is happening. They calmly wake up and start these new lives as though they have always been that way.
The cause: A wizard who lived there was spurned by a maiden he was infatuated with. His attempt to manipulate her memories into believing they were already together and that she loved him went horribly awry.
"Yn these landes, theye do ryde upone greate flowtinge beastes alike as those thate ye fyshermen do calle nawtilus; Ande these beastes, callede 'pyky-pyky' because of ye noises thate the beastes make, are troubelsome ande beastlye mountes, withe fowle temperes." -Telliamed ap Ynris, "Ye Westerne Landes".
(A levitating giant nautilus that makes a noise like "piki-piki" and is thus called a Great Piki-piki.)