If you haven't done so, or don't remember the story, now would be a good time to read The Heart of the Heart of the Eastern Green Forest. This tells the backstory of Taynair :
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I opened my eyes on a different world.
Neither Charles nor Peter seemed to notice. They, along with the horse, trudged along a road that was now pure black and unmarred by leaf litter or mud – but none of us made progress. It was as if we were in current that moved us downstream as fast as we rowed up it. On either side of the path, the trees and bushes shone silver. Pale flowers, blossoms grown from gem stones, grew in clumps in the covering silver moss, and translucent mushrooms sprouted in perfect rings.
This was the true Heart of the Eastern Green Forest.
I looked for, and saw a man seated on a boulder, a man with milk-white skin and no smile. His silver hair, adorned with twigs and leaves from the surrounding trees, hung to his waist, and he wore a circlet of fire. His robe was woven of muted colors that shifted as I watched., and he balanced a long sword between his knees. A dozen ladies lounged at his feet, dressed in soft colors and hard gems, their eyes and hair glittering silver.
Taynair, Prince of the Eastern Green Forest. Beware his smile, for the pleasure of the Silver-eyed is mortal pain.
His frost-filled eyes fell on me. "Speak."
I raised my hands.
"None of that! In my realm, you will speak!"
I had spoken to the Master of Paths, though my mouth felt no less empty than it usually did. And so I spoke to the Mirthless Prince. "Please let us go. We mean you no harm."
The corner of his mouth twitched – the beginning of a smile. "Why are you here?"
I shivered. "We are just passing through. Please, let us go."
His eyes appraised me. "Do you wish to bargain? A promise for a promise?"
My breath caught. Never bargain with a Silver-eyed, and never accept a promise from Prince Taynair. "No. But I will freely give you anything you ask."
The Prince of the Forest smiled openly, and I felt as cold as if standing naked in a frosted wind. "Give me a song, Bard. Give me a story."
"I have no harp," I protested, before I thought to stop. "I can make no music."
He leaned forward, his silver eyebrows flicking up as Master Meiltung’s did when we argued with him. "Sing with your heart, as you always have, Gerard, Bard of Songless Castle."
I started. "How do you know me?"
His smile widened, like a river of ice on the move. "Long have I waited for you, to hear your music and magic. Sing for me and remember me – though your path now curves away, we will meet again."
What would I play? For the people of the world I played of the spirit-lands. For a spirit, then, I need play of the world. So I sang of Lord Reinard and his follies, of our adventure together and its bitter end, and the words of the Dragon. Then I sang of the wider world, of the rising sun on a new-mown meadow, of the yule-fire crackling on the hearth. I sang of the Bardhall in Slatten and the one that I knew would never be again at Songless. As I emptied my heart to the Mirthless Prince, it filled with more. The cries of a newborn, the joy of a bride, the cold thud dirt filling in a grave.
The prince’s cold smile dropped away and was replaced by a gentle curve of his lips. It was a foreign, frightful thing to see, an unnatural warmth amid the chill.
At his feet the maidens gathered jewel flowers and wove them into daisy chains. One wove a coronet, the pale gems flickering within a nest of silver stems and leaves.
Abruptly Prince Taynair dropped his smile and raised his hand. "That is enough. Go, now, before the Night Riders travel the path."
The maiden weaving the coronet stood. "A gift! From Spara to your lady, the mother of your children."
Taking the offering, I brushed her fingers with my own – ice was never so cold. I put the coronet away in my pouch.
Price Taynair spoke again. "Remember Gerard – walk the path before you and always sing from your heart.
Then he let his hands fall, and the Heart of the Heart of the Eastern Green Forest disappeared, and with it the black path of the Night Riders.