As they were still choking on my words, I whirled and strode out of the room. In a moment I heard Father coming after me; I didn’t feel like trying to outrun him, so I turned to the nearest door, thought of the library, and stepped through just as he started to yell, “Nyx Tris—”

Then his voice cut off as if muffled by blankets. The library door swung shut behind me, and I was surrounded by rows of polished cherrywood shelves. The library was the largest room in the house, but it had been turned into a honeycomb of bookcases. I wandered down a row, trailing a fingertip across gold-stamped leather spines. I had spent so much of my life in this room; the scent of leather, dust, and old paper was like a friend.

From behind, I heard a gasp that was almost a sob. I turned and saw a girl sitting on the floor in a pool of dark skirts.

It was Astraia.

Had the mirror’s blurred image lied to me, or had I simply not noticed her changing? The fat had gone from her face; her jawbone was sharp and angular now, and though her lips were still plump, they were pressed into a flat line. She was dressed all in black, as she never had been since Father gave us leave to pick our own clothes, and her face was set in a hard, stoic expression that I had never seen on her before.

Her mouth opened, but no sound came out, as if she were still behind the glass.

“Astraia.” I dropped to my knees before her, then flung my arms around her shoulders. “I’m sorry. I’m so sorry.”

Her arms moved slowly to return the embrace. “Nyx? How—what happened?”

“I came back,” I said. I didn’t want to look her in the eyes again, so I made myself sit up and do it. “I couldn’t let you go on thinking that I was dead and hated you.”

“I knew you weren’t dead,” she said distantly. “I saw you at Mother’s tomb today. You and the Gentle Lord.” My heart jolted, but she didn’t accuse me, just went on, “If I’d only brought my knife, I could have—could have—” Her mouth worked silently a moment; then she swallowed. “I call to him every day, but he never listens.”

“I know,” I whispered. “He told me.”

Her mouth scrunched a moment, then smoothed. “Of course.” Then she sat very still, like an abandoned doll.

I took her hands. They felt small and cold. “Listen. I never should have lied to you about the Rhyme, I know that now, but I couldn’t bear to take your hope away. And what I said that morning—I was angry and scared and I didn’t really mean it. I have never hated you, and I’m sure Mother never did either.” The words, spoken so many times to the mirror, were now stiff and awkward in my mouth. “And I—if I could only take it back—”

“Hush.” She pulled me into her arms again, then eased me down to lay my head in her lap. Just as I had sometimes imagined she would. “I know he did terrible things to you.”

I choked out a laugh that was maybe a sob. She was so right and so wrong, she had no idea.

“I wanted to go with you,” she said, with the same empty calm. “If you’d ever asked, I would have crawled to help you. But you never wanted my help. You only wanted me to be your sweet and smiling sister. So I smiled and smiled, until I thought I would break.”

“I’m sorry,” I whispered helplessly, remembering all the times in our childhood when she had babbled about learning the Hermetic arts or knife fighting and I had rolled my eyes at her. I had always assumed that she didn’t mean it, because she was sweet and happy little Astraia.

She’d had the comfort of believing the Rhyme. But her happiness had still been almost as false as mine. And I’d ignored her pain, just as Father and Aunt Telomache had ignored mine.

“You’re really sorry?” She stroked my hair. “You want me to forgive you?”

“Yes.” I had said it a hundred times to the mirror, thought it a thousand more: Forgive me. Forgive me. Forgive me.

Her hand stilled. “Then kill your husband.”

“What?” I bolted up.

“He killed Mother. He defiled you. He’s enslaved Arcadia and ravaged our people with demons for nine hundred years.” Astraia looked me steadily in the eyes. “If you have any love for me, sister, you will kill him and free us all.”

“But—but—” I nearly said, I love him, but I knew she would never understand.

She smiled, the same sunny expression that for years I had assumed was simple and guileless. “I know. You think you love him. I saw you kissing in the graveyard. Or are you going to pretend you don’t enjoy bedding our enemy?”

“It’s not . . .” But I couldn’t go on; I remembered his kisses, his fingers running through my hair, his skin against mine, and it felt like my whole body was blushing.

Astraia’s smile vanished. “You like it.” Her voice was low and shaky. “All these years you were miserable. All these years I tried and tried to comfort you but nothing ever worked until at last I thought you were broken. I felt so useless that I couldn’t heal you. But really, all you ever needed was to kiss our mother’s murderer and become a demon’s whore—”

I slapped her face. “He is my husband.”

Then I realized what I had done and twisted my hands together, feeling sick. But Astraia didn’t seem to notice she’d been slapped.

“And a great honor that is.” She stood. “But I am still a virgin. I can kill him. If you have no stomach for saving Arcadia, get me into his house and I will do it for you.”

I surged to my feet. “You can’t.”

“You still don’t believe in the Sibyl’s Rhyme? Because I’ve done a lot of research since your wedding, and I am more convinced than ever. I’m willing to risk my life on it.”

I remembered how Ignifex had always taken the knife instantly away from me, how still he had been when I held it to his throat. How he had agreed to my bargain.

“No,” I said heavily. “I believe it now.”

“Then why not? Because it’s more important for you to have a man in your bed than for all Arcadia to be free?”

“No, because I love him.” The words ripped out of my throat and hung in the air between us. I couldn’t look Astraia in the eyes; I stared at the floor, my cheeks hot. “And because he isn’t the one who sundered Arcadia,” I went on quietly, desperately. “The Kindly Ones did that. He’s just their slave. He doesn’t even know his name. I told him— He said if he finds his name, he’ll be free. I promised I would help him.”