"Luke," she said, gritting her teeth, "I understand now. You have to trust me."

Kronos roared in outrage. "Luke Castellan is dead! His body will burn away as I assume my true form!"

I tried to move, but my body was frozen again. How could Annabeth, battered and half dead with exhaustion, have the strength to fight a Titan like Kronos?

Kronos pushed against her, trying to dislodge his blade, but she held him in check, her arms trembling as he forced his sword down toward her neck.

"Your mother," Annabeth grunted. "She saw your fate."

"Service to Kronos!" the Titan roared. "This is my fate."

"No!" Annabeth insisted. Her eyes were tearing up, but I didn't know if it was from sadness or pain. "That's not the end, Luke. The prophecy: she saw what you would do. It applies to you!"

"I will crush you, child!" Kronos bellowed.

"You won't," Annabeth said. "You promised. You're holding Kronos back even now."

"LIES!" Kronos pushed again, and this time Annabeth lost her balance. With his free hand, Kronos struck her face, and she slid backward.

I summoned all my will. I managed to rise, but it was like holding the weight of the sky again.

Kronos loomed over Annabeth, his sword raised.

Blood trickled from the corner of her mouth. She croaked, "Family, Luke. You promised."

I took a painful step forward. Grover was back on his feet, over by the throne of Hera, but he seemed to be struggling to move as well. Before either of us could get anywhere close to Annabeth, Kronos staggered.

He stared at the knife in Annabeth's hand, the blood on her face. "Promise."

Then he gasped like he couldn't get air. "Annabeth . . ." But it wasn't the Titan's voice. It was Luke's. He stumbled forward like he couldn't control his own body. "You're bleeding. . . ."

"My knife." Annabeth tried to raise her dagger, but it clattered out of her hand. Her arm was bent at a funny angle. She looked at me, imploring, "Percy, please . . ."

I could move again.

I surged forward and scooped up her knife. I knocked Backbiter out of Luke's hand, and it spun into the hearth. Luke hardly paid me any attention. He stepped toward Annabeth, but I put myself between him and her.

"Don't touch her," I said.

Anger rippled across his face. Kronos's voice growled: "Jackson . . ." Was it my imagination, or was his whole body glowing, turning gold?

He gasped again. Luke's voice: "He's changing. Help. He's . . . he's almost ready. He won't need my body anymore. Please—"

"NO!" Kronos bellowed. He looked around for his sword, but it was in the hearth, glowing among the coals.

He stumbled toward it. I tried to stop him, but he pushed me out of the way with such force I landed next to Annabeth and cracked my head on the base of Athena's throne.

"The knife, Percy," Annabeth muttered. Her breath was shallow. "Hero . . . cursed blade . . ."

When my vision came back into focus, I saw Kronos grasping his sword. Then he bellowed in pain and dropped it. His hands were smoking and seared. The hearth fire had grown red-hot, like the scythe wasn't compatible with it. I saw an image of Hestia flickering in the ashes, frowning at Kronos with disapproval.

Luke turned and collapsed, clutching his ruined hands. "Please, Percy . . ."

I struggled to my feet. I moved toward him with the knife. I should kill him. That was the plan.

Luke seemed to know what I was thinking. He moistened his lips. "You can't . . . can't do it yourself. He'll break my control. He'll defend himself. Only my hand. I know where. I can . . . can keep him controlled."

He was definitely glowing now, his skin starting to smoke.

I raised the knife to strike. Then I looked at Annabeth, at Grover cradling her in his arms, trying to shield her. And I finally understood what she'd been trying to tell me.

You are not the hero, Rachel had said. It will affect what you do.

"Please," Luke groaned. "No time."

If Kronos evolved into his true form, there would be no stopping him. He would make Typhon look like a playground bully.

The line from the great prophecy echoed in my head: A hero's soul, cursed blade shall reap. My whole world tipped upside down, and I gave the knife to Luke.

Grover yelped. "Percy? Are you . . . um . . ."

Crazy. Insane. Off my rocker. Probably.

But I watched as Luke grasped the hilt.

I stood before him—defenseless.

He unlatched the side straps of his armor, exposing a small bit of his skin just under his left arm, a place that would be very hard to hit. With difficulty, he stabbed himself.

It wasn't a deep cut, but Luke howled. His eyes glowed like lava. The throne room shook, throwing me off my feet. An aura of energy surrounded Luke, growing brighter and brighter. I shut my eyes and felt a force like a nuclear explosion blister my skin and crack my lips.

It was silent for a long time.

When I opened my eyes, I saw Luke sprawled at the hearth. On the floor around him was a blackened circle of ash. Kronos's scythe had liquefied into molten metal and was trickling into the coals of the hearth, which now glowed like a blacksmith's furnace.

Luke's left side was bloody. His eyes were open—blue eyes, the way they used to be. His breath was a deep rattle.

"Good . . . blade," he croaked.

I knelt next to him. Annabeth limped over with Grover's support. They both had tears in their eyes.

Luke gazed at Annabeth. "You knew. I almost killed you, but you knew . . ."

"Shhh." Her voice trembled. "You were a hero at the end, Luke. You'll go to Elysium."

He shook his head weakly. "Think . . . rebirth. Try for three times. Isles of the Blest."

Annabeth sniffled. "You always pushed yourself too hard."

He held up his charred hand. Annabeth touched his fingertips.

"Did you . . ." Luke coughed and his lips glistened red. "Did you love me?"

Annabeth wiped her tears away. "There was a time I thought . . . well, I thought . . ." She looked at me, like she was drinking in the fact that I was still here. And I realized I was doing the same thing. The world was collapsing, and the only thing that really mattered to me was that she was alive.

"You were like a brother to me, Luke," she said softly. "But I didn't love you."

He nodded, as if he'd expected it. He winced in pain.

"We can get ambrosia," Grover said. "We can—"

"Grover," Luke gulped. "You're the bravest satyr I ever knew. But no. There's no healing. . . ." Another cough.

He gripped my sleeve, and I could feel the heat of his skin like a fire. "Ethan. Me. All the unclaimed. Don't let it . . . Don't let it happen again."

His eyes were angry, but pleading too.

"I won't," I said. "I promise."

Luke nodded, and his hand went slack.

The gods arrived a few minutes later in their full war regalia, thundering into the throne room and expecting a battle.

What they found were Annabeth, Grover, and me standing over the body of a broken half-blood, in the dim warm light of the hearth.

"Percy," my father called, awe in his voice. "What . . . what is this?"

I turned and faced the Olympians.

"We need a shroud," I announced, my voice cracking. "A shroud for the son of Hermes."