Camp Half-Blood, New York

Percy's brain was moving sluggishly from Zeus' literal slap to the Argo II that had sent it back to New York, so it took him a moment to realize what he was seeing, but even the sight of the monster army couldn't put a damper on his happiness at finally being back at Camp Half-Blood.

There was a vast army of monsters spread across the hills—cynocephali, two-headed men, wild centaurs, ogres, and others he couldn't even name—surrounding two tiny islands of demigods. At the crest of Half-Blood Hill, gathered at the feet of the Athena Parthenos, was the main force of Camp Half-Blood along with the First and Fifth Cohorts, rallied around the golden eagle of the legion. The other three Roman cohorts were in a defensive formation several hundred yards away and seemed to be taking the brunt of the attack.

Percy surveyed Half-Blood Hill and felt something warm bloom in his chest. He hadn't been back since the winter break, when he'd spent barely a day there before Hera had abducted him and put him to sleep for months. He recognized most of the faces down on the hill—Malcolm, Nyssa, Lou, Katie, the Stoll brothers—and couldn't stop smiling. Even seeing Clarisse's grim face was a welcome sight after so long.

He spotted Grover in the crowd with some satyrs and nature spirits and his smile widened so much it hurt his face. G-Man. He must have felt him through their empathy link, because Grover looked up at the dragon and smiled. Percy could have cried.

Then Frank the dragon dipped a bit in the sky and Percy's stomach dropped. Giant eagles circled their air party—Jason and Piper riding the winds, Frank as a dragon carrying Hazel, Annabeth, and Percy—and he was reminded vividly that there was still Gaea to deal with. Reunions could happen later.

"Hazel!" Jason yelled. "Those three cohorts are in trouble! If they don't merge with the rest of the demigods—"

"On it!" Hazel said. "Go, Frank!"

Dragon Frank veered to the left and Percy's stomach went for a whole rollercoaster ride. In one of Frank's claws, Annabeth yelled, "Let's get 'em!" In the other, Percy closed his eyes and screamed, "I hate flying!"

Percy felt them descending and opened his eyes, preparing himself for battle. He still felt on edge after the fight at the Acropolis and what he'd done to the giants. They deserved it, sure, but that wasn't something Percy normally did. It was unnatural and scary, for both him and the people around him.

He clutched Riptide tighter, vowing to use his powers only if absolutely necessary to defeat these monsters and Gaea.

Cheers erupted behind them as Jason and Piper joined with the Greeks and Romans up on the hill. Frank gently dropped Percy and Annabeth in the midst of the other three Roman cohorts, then plowed into the closest line of monsters and breathed fire on the next. Hazel leaped from his back and landed on Arion, who had materialized out of thin air like usual.

Most of the Romans recognized Percy and cheered when they saw him. He and Annabeth didn't need to speak; they rushed to the front and began hacking through the monsters. For a few minutes, all Percy saw was talons, teeth, hair, and tails as he fought to give the Romans a reprieve. With Percy's new armor in place—courtesy of his father—he was better protected than he had been since leaving Camp Jupiter, so it was all too easy.

Behind him, he heard Frank shouting orders at the Romans and they obeyed him without question. The cohorts tightened their formation and began following Frank through the horde of monsters towards the rest of their forces up on Half-Blood Hill. Arion and Hazel flanked on the left, and Percy and Annabeth took the right.

Frank yelled in Latin: "Repellere equites!"

A massive herd of centaurs parted in a panic as the three cohorts plowed through in perfect formation, their spears bright with monster blood. Hazel was beaming at Frank with pride. Percy felt it too—he was proud to have watched and helped Frank become an amazing praetor.

Now that the way was clear, Percy spotted the rest of the Romans and Greeks atop the hill. Reyna was riding around on a new pegasus. Jason and Piper were fighting as well as they always had. The Greeks and Romans were working together better than Percy had hoped.

"Ave, Praetor Zhang!" Reyna called.

"Ave, Praetor Ramírez-Arellano!" Frank said. "Let's do this. Legion, CLOSE RANKS!"

A cheer went up among the Romans as the five cohorts melded into one massive killing machine. Frank pointed his sword forward, and from the golden eagle standard, tendrils of lightning swept across the enemy, turning several hundred monsters to toast.

"Legion, cuneum formate!" Reyna yelled. "Advance!"

Percy and Annabeth pushed their way through the heavily armored warriors and finally reached the top of Half-Blood Hill. When the Greeks spotted them, they cheered louder than the screaming monsters. Grover tackled Percy in a hug so fast he almost impaled himself on Riptide.

Percy grinned and hugged him back, but he pulled away quickly. "Fight now. Talk later?"

Grover nodded and hefted his club.

Percy looked at the Greeks again and was momentarily surprised to see them staring at him expectantly. Apparently, even after going missing for half a year, they still saw him as their leader.

There wasn't time for an eloquent speech like he'd given beneath the Empire State Building at the beginning of the Titan's invasion of Manhattan. Percy just raised his sword and shouted, "Greeks! Let's, um, fight stuff!"

It seemed to work. They yelled like banshees and charged.

Percy's thoughts were quickly consumed by the battle raging around him. Despite the overwhelming numbers, the Greeks and Romans seemed to be doing well. Percy was beyond relieved that the rift between them seemed to have been mended—the giant, gleaming Athena Parthenos statue probably had something to do with that.

Percy was feeling good about the battle, except for two big questions: Where was Leo? And where was Gaea?

Unfortunately, he got the second answer first.

Under his feet, the earth rippled as if Half-Blood Hill had become a giant water mattress. Demigods fell. Ogres slipped. Centaurs charged face-first into the grass.

AWAKE, a voice boomed all around them.

A hundred yards away, at the crest of the next hill, the grass and dirt swirled upward like the point of a massive drill. The column of earth thickened into the twenty-foot-tall figure of a woman—her dress woven from blades of grass, her skin as white as quartz, her hair brown and tangled like tree roots.

"Little fools." Gaea the Earth Mother opened her pure green eyes. "The paltry magic of your statue cannot contain me."

As she said it, Percy realized why Gaea hadn't appeared until now. The Athena Parthenos had been protecting the demigods, holding back the wrath of the earth, but even Athena's might could only last so long against a primordial goddess.

Fear as palpable as a cold front washed over the demigod army.

"Stand fast!" Piper shouted, her charmspeak clear and loud. "Greeks and Romans, we can fight her together!"

Gaea laughed. She spread her arms and the earth bent toward her—trees tilting, bedrock groaning, soil rippling in waves. Monsters and demigods alike started to sink into the ground. One of Octavian's onagers capsized and disappeared into the side of the hill.

Percy's feet started to sink and his heart leapt into his throat. For a split second, he was back in Alaska—but he couldn't let that fear control him. He wasn't sinking nearly as fast as he had then, and he was back home at Camp Half-Blood with his friends all around him. He shoved down the fear and nailed a mental wooden board over it to keep it in place.

"The whole earth is my body," Gaea boomed. "How would you fight the goddess of—"

FOOOOMP!

In a flash of bronze, Gaea was swept off the hillside, snarled in the claws of a fifty-ton metal dragon.

The dragon had Festus' head, and now that he could see its entire body, Percy realized with a jolt why it had always looked familiar. It was the same haywire bronze dragon that he, Annabeth, and Silena had dug up and reactivated to save Beckendorf from the Myrmekes' hive years ago.

Festus rose into the sky on gleaming wings, spewing fire from his maw triumphantly. As he ascended, the rider on his back got smaller and more difficult to discern, but Leo's grin was unmistakable.

"Pipes! Jason!" he shouted down. "You coming? The fight is up here!"

As soon as Gaea achieved liftoff, the ground solidified.

Demigods stopped sinking, though many were still buried up to their waists—thankfully, Percy had only sunk a few inches. Sadly, the monsters seemed to be digging themselves out more quickly. They charged the Greek and Roman ranks, taking advantage of the demigods' disorganization.

A few feet away, Jason put his arms around Piper's waist, about to take off and pursue Leo, Festus, and Gaea. Percy yelled, "Wait! Frank can fly the rest of us up there! We can all—"

"No, man," Jason said. "They need you here. There's still an army to defeat. Besides, the prophecy—"

"He's right." Frank gripped Percy's arm. "You have to let them do this, Percy. It's like Annabeth's quest in Rome. Or Hazel at the Doors of Death. This part can only be them."

Percy grimaced, trying to find a valid argument. But there wasn't one. They were right. The demigods needed him down here, and it wasn't like the fight up there would be easy. Only Jason and Frank could actually fly, so the rest of them would only get in the way.

But he could tell that this was the end. Gaea's defeat was imminent, and Percy wanted to be there. He wanted to make sure this was finished, and be there to protect his friends.

A flood of monsters swept over the Greek forces, breaking Percy from his stupor. Annabeth called to him, "Hey! Problem over here!"

Percy took one more look at Jason, Piper, and Leo up above, slowly growing smaller as they ascended. Something was about to happen. This was the moment Kymopoleia and Nike were talking about. The sacrifice was coming. The prophecy was about to be fulfilled.

And of Jason, Piper, and Leo, only one of them had been present when Nike made her prediction.

The roars of monsters spurred Percy into action and he ran to join Annabeth even as his thoughts spiralled. He stabbed, slashed, rolled, parried, over and over again. He spared a glance at the sky whenever he had a chance, seeing a steadily growing hurricane of fire and lightning with Leo, Festus, Jason, Piper, and Gaea in the middle. The sinking feeling in Percy's gut grew stronger with each second.

He let out his fear on the monsters. He kept a tight lid on his powers, relying on Riptide alone. He worried that if he gave in, something more inside him would break. After the Acropolis, he felt lopsided, like he was fighting with an ankle weight on one leg.

Percy heard something like a high-pitched scream in the distance and looked up. The fireball in the sky was now so bright it hurt to look at. A blazing comet was streaking toward it, looking like it had come from one of the Roman onagers. The comet intercepted the ball of fire and the explosion turned the entire sky gold.

He had a moment to worry for his friends, but then he saw a dark shape falling through the sky. As it came closer, he recognized it as Jason and Piper, both unconscious. Rescue eagles snatched them out of the sky and carried them to safety.

As the fire and smoke dissipated, Percy scanned the sky for a sign of Leo and Festus. There was none.

Percy locked down his grief momentarily to deal with the monsters. Gaea had not resurfaced, so Percy hoped that meant she was gone. They'd have to wait until Piper and Jason woke up to find out what had happened.

With their leader gone, the monster army fell apart under the combined assault of the Greeks and Romans. They were all either destroyed, or they fled in terror.

The rest of the day flew by. Nico told them what happened to Octavian. They started counting the bodies. As Half-Blood Hill cleared, Percy found Annabeth. Her game-face was on—ordering the Hephaestus cabin to scour the valley for Leo and Festus, organizing the infirmary, coordinating cleanup with the Romans. But he saw behind her mask—she was as worried as him.

An oath to keep with a final breath.

Percy doubted Leo could have survived that explosion, even as a fire-resistant son of Hephaestus. Piper wasn't with him, so she hadn't been able to give him the physician's cure. Percy hadn't had a chance to talk to Nico yet, but he recognized the look in his eyes. Nico had felt something in that explosion, and it wasn't just Octavian's death.

Since Percy took on the Curse of Achilles, he'd thought of himself as the shield. He was the one who was supposed to put himself in front of the others and protect them. With his abilities and invulnerable skin, anything less and he'd be letting himself down.

But he hadn't done it this time. Percy had failed Leo.

The next day, Piper and Jason explained what happened, the council of Cloven Elders announced that they couldn't sense Gaea's presence, they held a muted victory celebration and burial ceremonies, and Hazel confessed that she'd given Leo the real physician's cure. When he had a break between cleanup duties, Percy went off on his own.

He settled at the canoe lake, sitting on the pier and swinging his bare feet in the water. It felt strange to be home again after so long away. The water was helping to calm him a bit. It probably would have done more if he fully submerged himself, but he wasn't ready for that, even if he knew that the danger was over and that he was safe here at Camp Half-Blood.

He couldn't shake the feeling that he should have done something, that he should have done a better job of protecting everyone. He wanted to scream at how unfair this all was, how much they had sacrificed to save Olympus once more. He had half a mind to storm on up to the Empire State Building and give the gods a piece of his mind.

"I know that look."

Annabeth's sudden appearance startled Percy, his hand jumping to Riptide. She laughed as she sat next to him, swishing her feet in the lake.

Percy kissed her and put his arm around her. She hummed happily and leaned into him.

"What look?" he asked.

"The look that means you're blaming yourself for everything."

Percy frowned. "Aren't you supposed to be overseeing the repairs?"

"I took a break. And don't change the subject." She inched out from under his arm and turned to face him. "There was nothing any of us could do. Leo's plan—I hate it, but it was a good one. It worked. And it had to be him. You know it couldn't have been anyone else."

"I should have seen it coming. Nike warned us. Maybe I could have—"

"Percy, you can't protect everyone." She took his face in her hands. "I know how hard it is to let others step forward. I hated leaving Bob and Damasen down there, and I hate that Leo might really be gone. But we have to accept it."

Percy couldn't meet her eyes. "That doesn't mean it's easy to do."

She sighed. "No, it's not."

Percy looked down at his hands in his lap. He reached out and lifted a coil of water into the air, twisting it into the shape of Festus the dragon. His heart ached. He let the figure drop with a splash.

"I, uh . . . I thought you'd be scared of me after what I did at the Acropolis," he admitted. He remembered the promises he'd made to her on the Argo II once they'd gotten out of Tartarus. "I broke my promise."

Annabeth took his hands in her own. She took a deep breath, and Percy wasn't really surprised when she said, "I was scared. At first." He nodded, and then she continued. "But not of you. I was scared for you. You did what you had to do and you saved us. And I know you'll never do it again."

She ran a hand through Percy's hair, and he finally looked up at her. He saw only love and concern in her eyes. "I'm just worried about what it did to you," she said.

The crack inside him only seemed to have grown with each day. If it got too big, what would happen? Would he snap and go darkside, or would he just shatter like a piece of glass?

He was afraid it might be the former. And if that happened, he needed to know someone could stop him. He needed to be just a regular demigod again.

He took a deep breath. "It feels like something has broken inside me. I keep wanting to use those powers again. So I need the Curse of Achilles—"

"I know," Annabeth interrupted. "Once things cool down here, and once you go visit your mom, we'll make the trip to Camp Jupiter. And the other thing . . . we'll figure it out together."

Percy's shoulders dropped in relief. He pulled her close and hugged her tight, wondering how, with his awful luck, he had still managed to be so blessed as to have Annabeth by his side every step of the way.