The image
"I grant to you a soldier who has no heart. One who will not falter in the darkness. This soldier who has no heart is your twin image. A shell of yourself that you will shed when your song commands it." — Igos du Ikana
A young Link, sitting on top of the island above the water temple was thinking deeply. He had recently come home from his adventure in Termina, and wanted time to himself. Even though it was only an hour away until the Princess' feast was planned, Link was a day away on foot. He was at Lake Hylia. He had an odd felling ever since the ancient castle of Ikana he had gone through. The castle itself was not what got him wondering, but the elegy of emptiness he had learned. It struck a cord in his emotions, what the king has said, after teaching the tall blonde the song. "I grant to you a soldier who has no heart. One who will not falter in the darkness. This soldier who has no heart is your twin image. A shell of yourself that you will shed when your song commands it." Link couldn't place it at first, why did this description sound so familiar? He didn't understand until he really thought about it.
It was talking about a mirror image, one who seemingly had no heart. One without fear of darkness. Perhaps, Link thought to himself, perhaps it means something deeper. Maybe it even means that the creature described was once darkness itself turned to light. It came to him suddenly, it almost made the teen cry out in victory. The king had not only told him who, but he had also given him a means to find the other. To find his counterpart. To find Dark Link.
The 15 year old blonde took out his fairy ocarina, the one from Saria, and placed it too his lips. He could see the dark teen clearly in his mind. He played the notes, and turned them into a song, singing lyrics in his mind.
'To this world, I call a soldier. A soldier whom, had once no heart. Part of darkness, that revered its own fate. A similar image, to one that is close. A shell of a hero, that has thought of its own.'
Link placed the ocarina down on his lap, and decided on singing the lyrics quietly. He felt magic stir around him. And a dark presence behind him. He turned and smiled, to see a twin. One exact copy of himself. Except for his colors. He has silver hair, red eyes, and black clothes.
The Dark copy spoke, "I grant to you a soldier whom has earned his heart. One who will not falter whether in light or dark. This soldier whom is holder of a darker twin image. A shell of yourself that you wiled into existence."