Gimli to Aerlinn, at Berendil's tavern:

"Elsila was of Hollin. She was a natural healer and was said to possess extraordinarily beautiful eyes. Like a muted rainbow they were grey and sky blue and dark blue all together."

"You are a poet, Gimli." I had a sudden thought. "Is that why Thranduil is said to covet those jewels especially? They remind him of her eyes?"

"Just so."                 

- from "Tell This Mortal, or How Legolas Left Middle-earth" 

Elsila's Eyes

Elsila of Hollin sits in her chamber at the Hall of the Elven-King and thinks her enigmatic, shielded thoughts. Her feet are bare but she wears her customary house robes: a silvery-grey gown and a girdle of  blue and dark blue. The gown mirrors the colors of her eyes exactly. They are the most unusual eyes of anyone at Thranduil's court. Not Huntress's Noldori grey, or the Teleri's turquoise, or the summer blue of Thranduil and Elwen, or even the changeling eyes of Legolas can match them.

Elsila's eyes, in the centers, are bright grey, almost white, like bright sun behind a cloudy morning. But like the clearing day, the grey gives way to blue, and finally a darker blue surrounds all. Sometimes the grey is stormy, sometimes steely, sometimes pearly. But always there is bright grey, blue, dark blue. Long ago Thranduil took one look into those eyes, and fell. He has not reached the end of his fall and he never will while Arda endures.

Thranduil has many skills. He is a good king, an excellent father to Elwen and Legolas, an accomplished battle strategist and author of a treatise called "The Art of War;" few can equal his swordsmanship; his sense of humor surpasses most Elves and the ladies love him for it; and when he was a youth he loved to design and paint.

When he first met Elsila, Thranduil desired to paint her eyes. He collected paints that he made himself and linen-covered pallets on which to paint. He made brushes and pens, and he used hair from his own head to make his favorite brush. He stayed chambered for one moon's passage while he painted and dreamed of love.

When he finished, Thranduil the brave, who fought at the Battle of the Last Alliance, who cleared the Greenwood of Orcs, who became king by his own hand, was afraid. He did not wish to show his painting to his love. He could not paint her eyes. He could not paint his love. He could not bear her silence or worse, her kind remarks.

But then her gathered his courage in both hands and took Elsila to see the painting - the final version of course; not the earlier pieces. Elsila looked at the linen pallet on the artist's stand - it was a large work. She viewed it from across the chamber, and then she walked forward and studied it close up. This is what she saw:

The sky above the Great Greenwood is in late summer. A rainstorm has occurred, cooling the heat and refreshing the green growing things. Bright grey clouds reign, enthroned in the vault of the sky. But wait, here comes the summer wind on thick brushstrokes of blue paint, bringing white knights on cloud horses who tumble about the storm's skirts. One knight reaches out, first flirting, then wooing, now winning the storm's heart. His blue banner encircles and calms the stormy grey to peace, edging into the dark blue of twilight with its silver stars.

"These are your eyes," said Thranduil, swallowing hard.

Elsila put her arms around his neck and kissed his lips. The next day they exchanged silver bride pieces, and the next year they wedded.

Thranduil's Song

I did not see your eyes at first.
I saw you on that Rohan horse
For which we came to trade,
I and my father.

You did not wear your robes that day.
You bore your bow and rode away
In breeches, boots and shirt.
You were beautiful.

Your parents bade us to your hall.
Your folk prepared a feast, a ball.
And there I saw your eyes,
Silver, blue, dark blue.

Till then my days had all been free.
Till then my heart belonged to me.
May all my freedoms die
In Elsila's eyes.

NOTES

1. On canon:
Hollin where Elsila lived as a maid existed up through 1650 of the Second Age. Thranduil met her sometime between 700, when he moved to the Great Greenwood, and 1500 or so, while Hollin still enjoyed its peace and accomplishments. Rohan did not exist then, but a horse-loving folk that were forbears of the Rohirrim could have lived and traded their horses up and down the southern reaches of the Misty Mountains.

2. Elsila's tri-colored eyes - such people exist, and I have seen one. I'm told it is a genetic mutation, although everything else about the appearance is normal.