Percy uncapped Riptide, and Kronos unsheathed backbiter. The two rushed at each other, and immediately Percy knew this wasn't going to be easy. Luke was already an incredible swordfighter–and combined with Kronos's powers, he was giving Percy a hard time. While not as fast as Iapetus, his strikes were deadly and precise. But Percy kept blocking and parrying, even landing a hit on Luke's cheek. But to his surprise, it glanced off like his skin was made of metal.

There was a flicker of annoyance on Luke's face before he recollected himself. Kronos had shifted all his focus on Percy now, so the rest of the demigods were free from the time spell. Percy was frantically trying to figure out what he'd just seen. Then it clicked. Annabeth had told him about a place–the River Styx. It was how Achilles had become such a strong warrior. If you swam in the water, you would become invincible. But like everything, there was a catch. The River Styx had also given Achilles his famous weak spot, the Achilles Heel. Luke must've done the same thing. If that was true…then he must have a weakness somewhere. Percy just had to find it.

He went on the defensive, looking for any tells in Luke's body language. Kronos was no longer enjoying the fight. Percy was no longer the impatient teenager he had fought so many years ago. Time had made him more patient and tactful, especially in battle. Even with a power Percy didn't quite understand yet, he could at least stand his ground against the titan of chaos.

After several minutes of being battered by backbiter, Percy started to notice something. He never lifted his left arm too high, almost like it was injured. That must've been his weak point. But where? If Percy struck without knowing, it would give him away, and there'd be no chance of winning.

Percy made a move that forced Luke to lift his arm to block. Luke immediately stepped back and dropped his shoulders. There was definitely something fishy going on. Percy tried to think. Maybe it was the upper rib cage? His shoulder? He had to at least try it.

He slashed at Kronos's shoulder, but it took a full minute of focus just to land a strike, only for it to glance off his skin again. But he was getting warmer—Percy could tell by Luke's reaction. He kept going, until Percy managed to roll under one of Luke's strikes, slashing upwards at his rib cage. Kronos howled in pain, and Percy knew he'd found his weak spot. He took advantage of the moment to disarm Kronos, holding backbiter in his left hand.

Ichor dripped from the inside of his arm and onto the pavement. His expression was beyond upset. Percy breathed heavily. He wasn't looking too good, either. His whole body was bruised and cut. He wouldn't be able to keep up the fight for much longer.

"You are powerful, Perseus, but not powerful enough. Even in this…this weak body, I have still seen more than you ever will. In my divine form I could crush you like an insect."

"Iapetus said something like that too. Guess where he is?" Percy breathed heavily. "Well, part of him anyway. One part is on the sidewalk–the uh, speaking half might've rolled off onto the road."

Kronos scoffed, seemingly unphased.

"It is no matter. He will regenerate–even if it takes years."

"Maybe so. But I know what you did to Luke. I know you swam in the River Styx. Even with all that power, you're forgetting something. You're in Luke's body now, and demigods have a whole lot of weaknesses. I should know–I was one."

Percy tried to sound brave, but on the inside he faltered. He didn't want to have to kill Luke. He was desperately thinking, trying to find another way.

Kronos grit his teeth in anger. Suddenly he fell to one knee and clutched his chest, like he had just been punched. Luke's voice cried out in pain.

"Luke was much stronger than you thought, huh?" Percy held out Riptide. "You'll never attain your divine form. Not so long as I'm alive. And since I'm immortal, well…you get the idea."

Kronos looked up at him with hatred in his eyes. Then his expression shifted. Tears began to fall from his eyes. Percy hesitated, lowering Riptide.

"Luke…"

"No…p-please…Percy, my sword," he mumbled. "too far…" He pointed to Backbiter.

Percy swallowed hard. He knew what Luke was going to do. One final act of heroism–a sacrifice that would end the titan war for good. He always imagined Annabeth would have been here with him, to think of something–anything, some kind of magic to save Luke. But even though they never said it, both of them had known the truth all along. There was no other way to defeat Kronos, not even with Annabeth's genius.

It took Percy a moment to gather the courage. He knelt down and handed Luke his sword. Luke's whole body shook, his hands barely able to hold the hilt of the blade. He raised his left arm, but then stopped. His face was red with tears.

"A-Annabeth. Make sure…s-she's ok. Tell her I…"

Luke choked on his words.

"T-tell her I loved her. B-but…like a sister."

"I will," Percy whispered.

"And tell Chiron I'm…s-sorry. for everything."

Luke closed his eyes, mouthing something to himself. Then, with a quick movement, Luke plunged the sword into his arm. Kronos and Luke howled in pain. It wasn't a powerful strike–but it didn't need to be.

There was no white light, no spectacle like with the gods. Like a stone, Luke's body fell limp on the road. His breathing was shallow.

"He's…he's finally gone. I…" Luke's voice trailed off. "I hope…my dad…"

"I'll tell him. You're a hero, Luke."

Luke nodded. One last breath of air escaped his lips, and then his chest stopped moving. Percy collapsed on the floor beside him, exhausted. He gently closed Luke's eyes, then wiped the tears from his face. Backbiter was covered in red blood, proof that Kronos had been destroyed. Percy forced himself to stand. The battle wasn't over yet–camp-half blood still needed his help.

He carried Luke's body through the streets of Manhattan, which were silent except for the distant echo of fighting. Percy could hardly see through the smoke. His arms were about to give out, but if anyone deserved a proper burial, it was Luke. He'd make sure everyone knew of his bravery, even the gods.

Monsters and demigods alike stopped fighting to watch Percy carry their dead master's body. Most of the monsters ran away in fear, while the few that stayed were quickly taken care of.

"Percy! I heard…oh."

Chiron placed his hand on his shoulder, a grim expression on his face.

"You did what was needed. You are a true hero, Jackson. Though…I wish there had been another way. He was one of my best students."

Annabeth emerged from the cloud of dust. She was hugging the other demigods, but her smile disappeared when she saw what Percy was carrying.

"Oh, Luke…No…"

She covered her face with her hands, and tears quickly followed.

"It was Luke," Percy said. "He was the hero in the end. I couldn't do it. This whole time, he was fighting Kronos…and in the end, he won. For the longest time, I thought that prophecy was about me. But I was wrong. We were all wrong."

Clarisse stood beside Annabeth, who drew her into a hug. She was still processing everything that had just happened.

A few hours later, all the demigods had made their way to Olympus, taking their fallen heroes with them. The rest of the day was dedicated to burials, giving an homage to every demigod and ally whom they had lost. Minor gods and goddesses began to fill the gardens again, grateful that their home was still standing.

Grover's shroud was the most beautiful of them all. Wildflowers adorned the soft cloth–the same flower he always said he wanted to be reincarnated as. Juniper was kneeling beside him, holding his hands.

I'm sorry, buddy, Percy thought to himself. He hadn't even gotten the chance to talk to him one last time. He felt a mixture of anger and sadness. He could hardly keep himself from crying. If only Percy had been there for him instead of fighting Kronos…maybe his best friend would still be alive. And it wasn't just Grover. So many of his friends were gone. Beckendorf, Silena, Nate…the list went on. Percy suddenly realized what he'd signed up for. To be immortal was a blessing as much as it was a curse. Even though he was with his old family, it felt like he was more alone than ever. He wished Calypso was here.

Annabeth designed Luke's casket, a stunning marble-white with gold. Two snakes coiled around it like vines, resembling Hermes's staff.

"Luke told me something before he died." Percy focused on Annabeth. "He said…he said he loved you. You were like a sister to him. The family he never had."

She clutched the beads on her necklace, her lip trembling. Nine beads for nine years at camp. Soon, there would be a tenth.

"I miss him. And Grover. It's not fair," Annabeth said.

"I know."

"Where will you go?"

"Home," Percy said. "First I need to see my mom. Tell her that I'm OK. Then, well…I have a family of my own to take care of."

She looked surprised for a moment, then nodded.

"Will you stay on Olympus? With Poseidon?"

"I can't say anything for certain. But if you ever need anything, remember–I'm only one golden drachma away."

They embraced one last time, and then in a flash of white light, Percy was gone, wandering through his old apartment building, until he saw his mother's face just down the hall, staring at him in shock. Percy smiled.