In To Rule In Amber, one of Betancourt's prequels of Nine Princes in Amber, references are made to a third culture (different from Amber or the Chaos), namely the Feynims. They do not use the Logrus nor the Pattern, but the "Keye". I lost my whole Amber collection, so I can't look up in the books at the moment. Is there any other references to this "Keye", either in the cannon books or the prequels ?
It is NOT mentioned in Zelazny's books.
It is only mentioned in Book 3 "To Rule in Amber" of Betancourt's prequels.
“It is tied to the Keye – ”
“The Keye…” She hesitated. “It is ancient, like the Logrus, and very powerful. There is no time to explain. Father must not ask the Feynim for help or protection”
“Whoa! The Feynim? Who are they?”
She knotted her hands. “They are ancients. Older than Chaos. You must stop him! He must not deal with them–it is forbidden!”
Its exact nature isn't quite known:
“Can you tell me anything about the Feynim?” I asked him.
“Not much.” He frowned. “Nobody has heard from them in generations, not since they mopped the floor with King Ythoc. They're mostly legends now… bogeymen to scare little children. How did Dad get in touch with them, anyway?”
“I don't know. They seemed interested in the Pattern.”
He nodded slowly. “That makes sense. They would be interested in a new primal power.”
“Do you mean the Pattern?”
“Yes. They were interested in the Logrus… that's what led to the fight with King Ythoc. They wanted to see it. He refused and invaded their lands. Ten years of fighting followed.”
“Dad let them see the Pattern.”
“Probably a wise move.” He frowned. “I wonder if they ever did see the Logrus…”
“Why would they be interested?”
“Who knows. It's not like they need it–they have their Keye, of course.”
“You know–like the old nursery rhyme. 'What turns no lock but opens all doors? The Feynim Keye of course…' “ His voice trailed off.
“I've never heard that before,” I said.
“It's just nonsense for kids.” He shrugged. “A grain of truth wrapped in sugar and rhyme.”
These were the only 2 mentions of Keye in the books.
Feynim themselves earned another couple of mentions, which didn't help much in answering your question either:
“What just happened?” I demanded. “Who were they?”
“The Feynim?” My father shook his head unhappily. “Allies, I hoped, but they refuse to get involved.”
“What were they?” I demanded. “They weren't like us – or the hell-creatures.”
“True. They are not of Chaos or Pattern, but older. Much, much older. And powerful. I am not sure they have a name as we understand it.”
I remembered Ish's odd comment about his true name having no meaning. “One of them was here,” I said. “Looking at the Pattern.”
“They have some interest in us and our doings. They thrive on other people's discord, I think. I sent you here to make sure they did not destroy the Pattern… or change it subtly to our disadvantage.”
“Can they do that?” “Possibly. Yes. I suspect they changed the last Pattern, but subtly, trying to fix it. They did not succeed, however.”
I stared at the Pattern. What powers they must possess, if they could do as much as Dad said. Changing the Pattern seemed impossible.
Dad sighed, but nodded. “Of course. I understand. Take care of it, my boy. A spikard is a precious gift. Perhaps even…”
“Perhaps invaluable against Chaos. I half remember something about them. Something I read or heard a long, long time ago… something about the Feynim and their war against Chaos…”
“They fought Chaos?” I gasped.
“It was a very long time ago. So long that no direct written records of the war survive.”
“I am not sure. All I know is that Chaos lost. The Feynim drove King Ythoc and his army from their lands, never to return. I think they used spikards for… something in the battle. A barrier?” He shook his head. “I cannot remember.”
I decided to try another tack. I said, “So… if we are the pawns… who are the players? The Feynim?”
“If we are pawns, they are knights.”
He chuckled. “The gameboard, perhaps. Or perhaps one small square…”
“You know I'm not happy with that answer.”
“It is the only one I have.”
He pulled something from a pouch at his belt and held it out. I craned to see. It looked like an ancient gold ring, inscribed with characters I could not make out.
“What is this?”
“The Sign of Chaos.”
It seemed to mean something to Uthor and the others around us. Uthor gasped. Everyone else shifted and muttered to themselves. Clearly they had heard of it. And clearly it meant something good.
“What is it?” I asked Nox in a quiet voice.
“An ancient signet,” he said in a hushed, almost reverential voice. “It was lost centuries ago–stolen by the Feynim. To have it back, most especially at this troubled time… it is a great omen!”