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The Otherworld operated by laws foreign to mortal logic but no less binding.
Rule of Hospitality:
Hospitality was sacred and reciprocal. If you entered an Otherworld hall and were offered food, refusing was grave insult. But accepting had consequences—eating fairy food bound you to the realm. The compromise was to accept graciously, take one small bite, and hope that courtesy satisfied without transformation occurring.
Similarly, if a mortal offered hospitality to an Otherworldly visitor (recognizable by their unearthly beauty or strange knowledge), generosity was rewarded. The visitor might leave gifts, blessings, or warnings. But stinginess brought curse. A farmer who refused bread to a wandering woman (actually a goddess in disguise) might wake to find his cattle dead, his fields barren.
Rule of Names:
In the Otherworld, names had power. To give your true name was to give control. Many mortals learned to use pseudonyms when dealing with the Sídhe: “I am called Wanderer” or “They name me Poet.” This was not lying (which the Otherworld punished) but prudence.
The Sídhe respected this caution. They themselves often gave titles rather than true names: the Green Knight, the Lady of the Lake, the Dark Druid. These were identities that could be discarded, changed, replaced. The true name remained hidden, protected, unspoken.
Rule of Time:
Mortal time and Otherworld time did not synchronize. The dangerous corollary: mortals in the Otherworld aged according to the mortal calendar, even when experiencing only days or weeks. A man spent ten years in Tír na nÓg (by his reckoning) and returned unchanged. But if he touched mortal earth—set foot on grass, let his boots contact stone—all ten years collapsed onto him at once. He aged a decade in seconds, crumbling to dust.
The only protection was to never touch ground. Some returning Otherworlders rode horses that never set hoof on earth, floating inches above grass. Others were carried in chariots, never stepping down. But eventually, accident happened. The rider fell. The chariot broke. And time claimed what it was owed.
Rule of Iron:
The Otherworld feared iron. Not bronze (which the Sídhe used for their own weapons and jewelry) but cold iron—the stuff of plowshares, horseshoes, mortal tools. Iron disrupted Otherworldly enchantment, dispelled illusions, wounded Sídhe flesh in ways that never fully healed.
This is why mortals carried iron when traveling near fairy mounds: a nail in the pocket, a knife on the belt, a horseshoe above the door. Iron was protection and weapon both. It said to the Otherworld: I acknowledge your power, but I am not defenseless.
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