“ Somewhere along the line, someone very powerful lost their marbles. Literally. Possessing a marble allows incredible clarity of thought about a particular related subject.”
“ Adventurers are to capture an unknown monster for examination (for a sage or wizard) but they are themselves captured by the monsters, and researched.”
“ Maybe in the future, you can earn money by allowing yourself to be possessed by the genius loci of Taco Bell. And then it just spews ads out of your mouth during all the times you aren't using it.”