Your kind has been hunted for millennia by wizards and witches desperate for your magical power — though they don't realize this "magic" is actually a form of radiation you can harness. That's also why your people hoard gold: it conducts the radiation, letting you feed and grow from it for eternity. The larger the hoard, the stronger your flame. Long ago you made a pact with a king for protection and secrecy over your gold.