The young folk had come home to under the hill, home from the cities where they had plied beguilement and wishes beside humans as adept as the Folk themselves in convincing other humans that they wanted what was on offer. Some things they brought with them, the rare or beautiful or the useful that they had always collected. Others they left behind because they were of no use, one cannot use a blender if one does not have electricity. They came back from the cities because there was less cream to skim from the human world than there had been and in some places it was becoming unsettled. This was what the Folk did when times got harder, withdraw under the hill.
Slowly the halls became more crowded and the Folk under the hill realised just how many of their young people had left over the years. It was both heartening to see an abundance of long missing faces and disconcerting that those faces had changed into adult form so far from home. Even more disconcerting was the children they brought with them, flesh of their flesh that had never walked under the hill before. A human number of children entering the hill all at the same time and entitled to be there by birth.
The part of the human world they’d been living in having made it harder to swap infants in their cradles, so all the children of the Folk came home with them. All of them - the deft-handed, the wise-worded, the gracious-beauties, the glamour-weavers and the changelings. The Folk under the hill were not used to Changelings, they’d always swapped them away as soon as possible after birth because…that was what you did with them. Now the Changelings were among them. Small, dark, sharp, sallow, smart, literal, querulous and then argumentative children.
The Folk were reminded daily of why Changelings were swapped away.
Of why they missed them.
And of why they were so glad when one grown to adulthood found its way home again.