“Fascinating,” Martin breathed, leaning back on the bags stacked behind him, lost in thought. “There are very old manuscripts within the library recording the accounts of the fey who lost their immortality. Many spoke of a growing difficulty in passing between worlds, that it became physically painful for them to do so. Some took it as a warning and left, never to come back, but some couldn’t help themselves and remained. The change happened swiftly and to nearly everyone at once; only a few were able to flee back to Arcadia, the rest no longer even possessing the ability to open paths. It was as though our link to our homeland had been severed.”

“What did they do?” I asked

“It was a panic, of course,” Martin replied. “They knew it was iron that was holding them back, but not how to rid themselves of it. Many tried starving themselves and forgoing water; others attempted to bleed themselves dry, believing they could remove the contaminant that way. There were casualties, but when they realized that they’d started aging, that their magic had begun to change, that they were no longer immortal, they tried anyway. Those ancient fey were still long-lived by our standards – hundreds of years – but with each passing generation, lifespans grew shorter. Now they are no better than the average human. In a few hundred years, perhaps we’ll live and die in the space of a handful of decades.” He sighed. “There have been some who have postulated that it is this world’s way of getting rid of that which does not belong, but that strikes me as fancifulness.”

“It’s a poison to you,” my gran said thoughtfully, tapping an index finger against one tooth. “One that is compounding over the generations. Has it caused trouble other than mortality?”

Poison.

“Birth defects; madness; and, as is the case with the Duke, hemophilia,” Martin said. “Though some of it might be caused by inbreeding, particularly amongst the aristocracy.”

Gran wrinkled her nose. “Vile habit. And what of those with mixed blood: human and troll? Are they similarly afflicted?”

Martin shook his head. “There isn’t a single case of an afflicted half-blood on record; and for the thousands of years our kinds have intermingled, the life expectancy of half-bloods has remained constant. Injuries inflicted with steel weapons on half-bloods heal at approximately the same rate as those inflicted by other metals. If not for the marked decrease in power, the injection of human blood into our lines might have been a viable method of adapting ourselves to this world.”

I heard everything he said, but my mind was all for the word poison. “Gran,” I said. “How do you cure poisoning in humans? With magic, that is?”