Nimue found the wizard where Morgana said she would, which was the first surprise, because Merlin had not let himself be found in twenty years.
He kept a hill in the west with a thorn at its crown and a low door in its side that no shepherd had ever reported, though the hill stood in plain sight of three valleys. Nimue walked up to the door as though it had been left open for her, because it had. Morgana had sent her with a single line of instruction — he will already know you are coming; do not pretend otherwise; he despises a pretence more than a threat — and so when the door opened on a passage that breathed cold stone and old smoke, and an old, old voice said out of the dark, "The Lake sends me a girl with a knife behind her smile; how flattering, at my age," Nimue did not smile, and she did not hide the knife, which was not a knife at all but the thing Morgana had taught her, the long patient craft of binding.
"Morgana is in the North," she said. "Her sister is dead. The cold has a face and the face has no name, and she says you will tell me why, and what it costs to end a thing that cannot be unmade the ordinary way. She says you owe her a true answer, for once, because you have spent her like a coin her whole life and never once told her the price written on her own back."
A long silence in the dark. Then a small warm light woke at the passage's end — not fire, something older and quieter — and she went down to it, and found Merlin.
He was dying. That was the second surprise, and the larger one. The harpers sing Merlin ageless, Merlin eternal, the serpent who outlives every king he makes; and here in the warm dark of his hill he sat wrapped in furs like any old man at any hearth, thin as a winter bird, his hawk's eyes filmed, his prophet's hands shaking on his knees. He had spent himself. Nimue understood it the way she understood everything now, fast and total: he had spent his whole long unnatural life holding the cold off a forgetful world, ward by ward, year by year, and the wards were failing because the warden was, and that — not chance, not Sebile's cleverness — that was why the seed had found room to wake.
"Sit," Merlin said. "You will want to be sitting for this." She sat. "Sebile spent her true name an age ago, when she put the cold on like a gown. A thing with no name cannot be unmade by naming, because there is nothing left in it to call. You know this; she told it to Morgana over a dead sister to frighten her, and she was not lying. The cruel ones rarely need to lie." He drew a breath that rattled. "There is only one way to unmake a thing that has spent its name, child, and it is the oldest and worst working there is, and your Lake walled up a whole well rather than teach it. You cannot speak such a thing's name. You must give it one. You must take a true name — a whole, living, person's true name — and you must speak it into the nameless thing, and bind the two together, name to namelessness, so that the thing becomes a person again, with a person's single mortal shape, that can then at last be ended. But a name spoken into another cannot be un-given. Whoever gives Sebile a name to die by, ties their own self to her death — spends their name into hers — and walks out of it unmade. Nameless. The way Morgana walked out of the first ending; only this time there is no warm island to forget herself on after. This time it is the whole of her, given away into a stranger, forever."
Nimue sat very still in the warm dark and did the arithmetic that the cruel and the kind both have to learn, and arrived where Merlin had already arrived, decades ahead of her, and hated him for it.
"You sent me here knowing I would see it," she said. "That the only true name big enough and freely given enough to spend into Sebile — the only one that could end her and let Morgana keep her father and her self both — is yours."
"Every prophet," said Merlin, and smiled, and it was almost kind, "wants to choose his last sentence. I have spent four hundred years arranging other people's endings. Grant me the small vanity of arranging my own. I cannot carry myself north; I am too far gone, and the cold would feel me coming and run. But you can carry me. You have the binding in you — Morgana put it there, and I helped her, long ago, for exactly this hour, though she does not know it and you must never tell her. Bind me into something a girl can carry in a satchel to the North. A stone. A crystal. The old way. And when she stands on that island with no answer left, open the satchel, and let me be the answer." He held out one shaking hand, and in it was a shard of clear stone, and Nimue understood she had not come to murder a wizard after all. She had come to help one lie down.
"They will say I trapped you," she said. "The songs. They will say the Lake-girl bewitched old Merlin into a cave and shut him up out of wickedness. They will make me your gaoler and never your friend."
"The songs," Merlin said, "will say a great many wrong things about a great many women in this story. You and Morgana will be the worst served of all, the cleverest punished hardest, as is the way of songs. Take comfort, child: somewhere a frightened boy in a grey-green cloak is writing the true account, and hiding it where the victors will not think to look." He closed her fingers around the shard. His hand was already growing cold, and he let it, gladly, the way you let go of a thing you have carried too long. "Now. Bind me, and go north, and tell Morgana her wizard is in her pocket and her last answer with him — and tell her, from me, the one thing I never told her to her face and should have, the first time I called her little Reader over her father's grave."
"What?"
"That she was never the villain of this story," Merlin said. "She was only the one who paid. Now bind me, daughter of the Lake, before I lose my nerve and prophesy my way out of it. I have foreseen ten thousand endings. Let me, for once, be surprised by one."