I find this so interesting that so few understand soul mates or elves. I too have seen the dark crystal and it is based more on the likeness of good and evil not ajoined souls. I am sure we have all met those wonders that go from one person to another never marry like they are looking for someone. These are the ones who are already joined to another. Lost without the other. Sometimes taking several life times to find one another. It is based out of a belief of recarnation. That to find true love in one life may join you forever and when recarnated they begin the journey to look for that person again until found.