I dared to look up then. Astraia had tilted her head thoughtfully to one side.

“The Kindly Ones are real?” she said.

I nodded. “Yes. In the days before the Sundering, they struck bargains with men like the Gentle Lord does now. And I think the last prince must have made some bargain with them, because they sundered Arcadia, created the Gentle Lord to administer their bargains, and made the last prince his slave.”

“So you know how the Sundering happened.” Astraia’s voice was quiet, thoughtful. “You know that the last prince is alive and kept in slavery. With what you’ve learnt and the knowledge of the Resurgandi, you could probably save us all. And your concern is for a servant of the Kindly Ones?”

“No—but—” A new thought suddenly struck me, and I drew a breath. “The Rhyme doesn’t promise that it will end the Sundering or destroy the demons, it just promises that it will destroy him.”

“So?” said Astraia. “It would avenge our mother. It would stop him sending his demons against us. We can solve the Sundering at our leisure once he’s dead.”

“You don’t understand,” I said. “He doesn’t send the demons against us. He’s the only one holding them back. When they hurt people, it’s because they escaped against his will, and he hunts them down. If he were gone, they would tear us all to pieces.”

I felt a sudden surge of hope. I didn’t understand this new Astraia—no, I had never understood who my sister was all along. But surely she had to see the logic of my argument. Surely she had to accept it.

Her forehead creased thoughtfully. “The chief servant of the Kindly Ones can’t always control his demons? Why would they leave him so little power?”

I shrugged. “They thought it amusing, I suppose.”

“Or he thought it amusing to lie to you.”

“He wouldn’t—” I started, then caught myself as her face started to twist in scornful disbelief. “Do you want to risk it?” I asked instead.

“No,” said Astraia. She seemed to consider it a moment. “Then before we kill him, we must find a way to end the Sundering and banish the demons.”

She spoke so confidently and matter-of-factly that it took me a moment to find my voice. “No, we need to find his name.”

“And if it’s possible to find his name, and if it’s true that it would free him, do you have any reason to believe that it would end the Sundering and free us from the demons?”

I didn’t, I realized with a cold, sinking horror. He’d only said that I would be free and he wouldn’t have masters anymore. Everything else was just my own foolish hopes.

“But we can’t kill him,” I protested. “I told you—”

“You have told me good reasons to be careful,” she said. “You have told me that so long as he lives, demons will ravage our people. You have told me that so long as he lives, he will still lure people into twisted bargains.” She stepped closer, until our faces were only a breath away. “You have told me that you want him alive, though it means our mother will lie unavenged, and his bargains will punish both guilty and innocent, and demons will crawl out of the shadows and torment people until they die screaming every day.”

There was no anger in her voice now, only perfect, unbending conviction. I couldn’t move, couldn’t breathe, couldn’t look away from her relentless gaze.

“Is that not so, sister?”

I wanted to shout, You don’t understand!—but every word she had said was true. People were dying every day, and I hadn’t minded if they kept on dying, so long as the one person I wanted stayed alive. Even though he was the one person who least deserved it.

In the end, all I could do was stare at her and whisper, “Yes.”

“You know he’s a monster,” she said gently. “However much you think you love him, you still know. Maybe he is enslaved, but if he really hated what he was doing, he could have killed himself any time.”

I shook my head, remembering how he had healed from the darkness. “I’m not sure they would let him die—”

“Am I telling the truth?”

“Yes,” I said helplessly.

She laid a hand on my cheek. “I’ve heard the stories about him. I don’t blame you for being beguiled. But if you do not help me, I will never forgive you.” Her lips curved in a sunny, vicious smile. “And I know that Mother will never forgive you either.”

My nails bit into my palms. She had every right to fling my own words back in my face, and she was probably telling the truth, as I had not.

“He trusts me,” I said. “You know how the gods judge traitors.”

“You must betray one of us. I suppose which one you pick depends on whom you love the most.”

I looked at her. She wanted me to break my promise with Ignifex, to betray him after he had given me absolute trust, to kill the only person who had ever loved me and asked nothing in return.

She was my only sister, the living image of my mother, and the person I had hurt the most when of all the people in the world she deserved it least. She wanted me to avenge ten thousand murdered souls and save all Arcadia from the terror of demons.

I remembered the screams echoing from Father’s study. I remembered huddling next to Astraia when she couldn’t sleep for fear the shadows would look at her. I remembered silently swearing, I will end this.

That oath, too, surely must be kept.

“Nyx.” Astraia cradled my face in her hands. “Please.”

I should have known, I thought dully. Why did I think that I would ever get to keep what I loved?

Why should I think that my love was more important than all Arcadia?

I gripped her hands and whispered, “Yes.”

Our fingers wove together. I felt like there was ice jammed into my chest.

“Swear to me,” she said, “by the love you bear me and our mother, by the gods above and the river Styx below, that you will destroy the Gentle Lord, rescue the last prince, and save us all.”

My heart thumped. I tried to speak, but my throat tightened. Memories of Ignifex flooded over me: His lips against mine. His hands as he slid the ring onto my finger. His voice in the darkness as he said, Please.

But he didn’t matter any more than I mattered. We were both wicked people, and we were both the ones who had to be sacrificed.

“I swear.” The words came out in a whisper. Then I swallowed and ground them out. “I swear by my love for you and our mother, by the gods above and the river Styx below, that I will destroy the Gentle Lord, rescue the last prince, and save us all.”