I thought about how a Worldfall could affect a siege. A city "falling" directly into a siege or out. The enemies trying to find their own way to the Feywild or the Normal World, or trying to catch and hold the city in one plane via magical means.
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For humans on the Feywild, I think one change might be personality. The Feywild is the bright mirror of the world. Every color is more intense, and so is every emotion.
How would humans change in such an enviroment? Would they embrace it, and you might see any quarrel in the tavern get into a brawl that seems to follow some "rules" to avoid real harm? People falling in love easily and intensively, but ending their relationship as fast as they got into it, with no regrets?
Or would they try to fight it, and would focus on meditation and maybe even drugs to calm their minds?
I think the Eladrin go already the "calm and completitive" route, so I think the humans should be "wilder". They just use some subtle rules to ensure that it doesn't harm them, physically or emotionally. I suppose a lot would also spend time to craft art objects or play music, to express their feelings. (Might be the only way for anyone getting into a depressed mode to avoid suicide). What they might lack is focus. They can't do anything for long, since something new comes to their mind and it demands more attention. They work different jobs and while what they do, they do good, they don't do it for long, so Eladrin rely on them only as temporary workers.