It is up to you, the DM to decide which memory but there is a chart here to roll what kind of category memory the LemLeaf stole.
LemLeafs are the lost souls of seafaring women, mostly former whores who died upon ship wrecked. No one knows why but the blue lit square that always either precedes them with their eyes unable to stray from it, or follows them, without eyes. Each LLeaf has a story for the PCs to figure out but the LLs all have some reason they are trapped by this square. It is up to the DM to decide what their particular story is, but if the PCs can figure it out, the LL is released of this trap and becomes the servant of whomever freed them. Usually this means a sex slave but they are eternally devoted in any case as fairy magic nymphs and automatically know the locations of all shipwrecks of any region.
Alignment: Variant. Hut hinged like a ghost, on completing her story.
HP: 2d10 for the spirit to go away, does not die because they're undead.