“ A secret MLM (pyramid) company that offers eternal life, but in fact it transfers the life forces of its members to those position 'above'. If you get high enough, (meaning you get enough new members) you start to enjoy the benefits. Maybe a willing sacrifice is much more effective for the transfer. But no one says, that a suddenly unwilling member, threatening to tell the authorities, may not loose it involuntarily... thus start people to vanish, and aged corpses are deposited somewhere safe.”
“ When you sleep, your soul briefly returns to the place where it was created/goes to when it dies, and seeks nourishment. Everybody's soul is created with a little link (or you could say a greater entity calls it back) to that place so that it can return easily, but upon death, the soul returns via that and annihilates the link as if returns.
Also, as an added thingy, you could say the entity supplying the link, or residue of the links themselves, (whichever) is the source of all arcane power.”
“ Marraige custom. The groom must prove his worth to the friends, family, and future wife. The best man is obligated to challenge the groom to a duel and the best man chooses the weapons. (can be anything, toothpicks, cotton balls, anything) If the groom wins then he proves his worth. If he loses then the bride will accept him for his faults and could sometimes gives him a task to accomplish before the wedding.”