Sebastian Vane was the most hated genius in London. Every critic who reviewed his work called him a master and a madman in the same paragraph, as if the two things were inseparable, which perhaps they are.

His studio was in Bloomsbury, a top-floor space with skylights that let in the kind of grey London light that makes everything look like a painting. The walls were covered in canvases. Each canvas showed a human figure with animal features rendered with a precision that was either divine or demonic. A woman with butterfly wings, the wings painted so realistically that you could see the individual scales on each wing. A man with serpent eyes, the pupils vertical slits that seemed to follow you across the room. A child with gills along its neck, the gills pink and delicate and terrifying.

"His brushwork is extraordinary," wrote the critic for the Times. "His subject matter is the work of a diseased mind."

Sebastian read this review in bed, with Isolde sitting beside him, painting his hand. She was his model, his lover, and the only person in London who could touch him without his flinching away. She was twenty-four, pale as milk, with dark hair that fell to her waist and eyes the colour of strong tea. She wore black always, because white, she said, was for people who hadn't seen what she had seen.

"What does it say?" she asked, not looking up from his hand. She was painting his fingernails a pale grey.

"Same as always. I'm a genius and I'm sick."

"Are you?"

He thought about it. "Yes. No. Both. Neither."

She smiled. It was a small smile, the kind that appeared and disappeared like a fish breaking the surface of dark water. "Then we agree."

The changes had started six months earlier. First, an itching between his shoulder blades. He thought it was a rash. Applied calamine. Didn't help. The itching moved deeper—under the skin, under the muscle, into the bone. He could feel something moving. Not pain. Pressure. Like something was pushing from the inside against the outside of his body, trying to get out.

He looked in the mirror one morning and saw that his shoulder blades were different. Protruding. Not much—just a centimeter or two on each side, creating small hills beneath the skin. And between the hills, the skin was thin and translucent and pink, like the inside of a butterfly's wing before the colour has developed.

He touched it. It hurt. Not sharply. Deeply. The kind of hurt that comes from the bone.

Isolde saw him looking in the mirror. She didn't say anything. She came behind him, placed her hands on his shoulder blades, and felt the protrusions.

"Oh, Sebastian," she whispered. Not fear. Not pity. Wonder. "They're coming."

"Coming?"

"Whatever they are. Whatever you've been carrying inside you. They're coming out."

He went to Dr. Helena Cross. She was thirty-five, one of the first women to practice neurology in London, and the only doctor Lord Ashford trusted. She examined him in his studio, which was perhaps the most unusual medical consultation in the history of British medicine.

Dr. Cross was methodical. She asked questions. She examined him. She palpated the shoulder blades. She asked him about family history, about childhood illnesses, about any exposures to chemicals or heavy metals.

"Nothing," Sebastian said. "My family is Irish. They drank. They died young. That's the family history."

Dr. Cross nodded. She pressed harder on his shoulder blades. Sebastian hissed through his teeth.

"Is it—do you feel anything? Flapping? Stretching?"

"There's pressure. Movement. Like something is unfolding."

She stepped back. Looked at him for a long time. Then she said the words that Sebastian would remember for the rest of his life, which was not very long:

"This is not a disease, Mr. Vane. This is evolution."

He laughed. It was a dry laugh, the laugh of a man who had heard every insult London had to offer and was still finding new ones. "Evolution. You're telling me I'm evolving?"

"I'm telling you that whatever is happening to your body does not fit any known disease pattern. The tissue between your shoulder blades is growing at an abnormal rate. The cells are dividing faster than any cancer I've seen, but they're not cancerous. They're—different. New. I don't have the vocabulary for it."

"Then don't use vocabulary. Use honesty."

"I'm being honest. I don't know what you are, Sebastian. But I know you're not sick."

He paid her. She left. Isolde stayed.

They spent the next three months together in the studio. Isolde painted him—painted the shoulder blades as they grew, day by day, the skin thinning, the colour deepening from pink to a translucent amber. Sebastian painted her—painted her in black dresses, in shadow, with eyes that were almost too dark, almost too alive.

The shoulder blades broke through on a rainy Thursday in November.

Sebastian was painting when he felt it—the tearing, sudden and sharp, like a seam splitting in an old coat. He dropped his brush. He turned to the mirror.

Two things were pushing out from his back. Not wings yet. Not fully. But membranes—thin, delicate, semi-transparent, like the wings of a bat or an angel or something that had never existed in nature but existed now, in his studio, in the grey London light, and were undeniably real.

Isolde screamed. Not in fear. In awe.

She came to him. She touched the membranes. They were warm. They vibrated slightly, like living things. Like hearts.

"Sebastian," she said. "They're beautiful."

They were. Amber-coloured, veined with thin red lines that might have been blood vessels or might have been something else. They were maybe a foot long, folded against his back like a fan that hadn't been opened. But they were real. And they were growing.

Every day they grew. Every day they changed. By December, they were three feet across, fully formed, the colour deepening to a rich gold-amber that caught the light and threw it back in ways that made the studio look like a cathedral.

Sebastian stopped painting others. He painted only himself.

The final portrait took three weeks. He painted himself as he was: pale, thin, grey eyes too bright, mouth set in a line that was almost a smile. And the wings—oh, the wings. He painted them with a devotion that bordered on worship. Each membrane, each vein, each tiny detail rendered with a precision that made them look less like anatomy and more like revelation.

When he finished, he stepped back. He looked at the canvas. He looked at himself in the mirror. And he saw that the painting and the man were the same thing—because the wings on the canvas were the wings on his back, and the wings on his back were the wings in his soul, and the wings in his soul were the only honest thing about him.

He invited everyone. Lord Ashford came, wearing his best coat and carrying a bottle of brandy that Sebastian refused to accept. Dr. Cross came, professional and curious and afraid in equal measure. Isolde came, wearing black and looking like death's favourite painting.

They stood in front of the portrait in silence.

Lord Ashford was the first to speak. He was a man who had seen everything London had to offer and had never been moved by any of it. But the portrait moved him. His eyes filled with tears. He did not wipe them away.

"It's you," he said. "It's exactly you."

Isolde stood beside Sebastian. She looked at the wings in the painting. She looked at the wings on his back. She said, quietly: "You're the most beautiful monster I have ever seen."

Dr. Cross said nothing. She simply nodded—the nod of a scientist who has witnessed something that cannot be published, cannot be explained, cannot be shared. Some truths are too large for language.

That night, at three in the morning, Sebastian dressed in his white suit—the one his mother had bought for his confirmation in Dublin, the one he had never worn because white, his mother had said, is for people who are confident in their place in the world, and Sebastian had never been confident about anything.

Now he was.

He walked out of the studio. He walked through the streets of London. The fog was yellow. The gas lamps threw long shadows. The city was asleep, or pretending to be. He walked toward the river.

The Thames was black and wide and smelled of everything London had ever thrown away. He stood on the bank and looked at his reflection. The wings were reflected too—golden, vast, beautiful, terrible, utterly and completely honest.

He stepped into the water.

The cold hit him like a fist. He did not resist. He let the water fill his lungs, let the wings spread in the current like sails catching a wind that existed only underwater, let himself sink toward the bottom of the river that had carried the secrets of this city for a thousand years.

The last thing he saw was the moon, breaking through the fog, shining on the water like a question that had no answer.

The portrait hung in his studio for three days after he disappeared. Max Goldstein came to see it. Lord Ashford came to see it. Dr. Cross came to see it. Isolde came to see it and stood in front of it for an hour and did not cry.

Max said nothing. He simply covered the portrait with a cloth and locked the studio door.

He didn't unlock it for a week.

When he did, he moved the portrait to the centre of the gallery, on its own wall, with a single spotlight and no label. No title. No price. No explanation.

Let them see it, he thought. Let them see what honesty looks like when it grows wings.

Nobody bought it.