The beach he surfaced on was crowded. When he started to walk out of the water, he was assaulted with a searing pain in his chest underneath the mark, as if it were being administered again. Stumbling backwards, he sat down in the water, resubmerging his chest, and the pain subsided to nothing. He sat there for minutes, mentally dissociating. He felt like he wanted to curse himself, his father, his brother, and everyone, and he knew he was enraged, but he felt such a mental disconnect from those emotions that he could not access them, as if he were outside his mind grasping toward feelings just beyond his reach. Eventually, he knew he had to move, so he crouched in the water so that it was up to his neck and fished for his shirt in his back pocket, then slipped it on as he stood.

Wandering around the busy city streets, he wasn't even sure what he was doing or where he was going. Russia was massive, and he didn't know where Anastasia was, nor did he speak the language. He occasionally tried sending her thought messages, to no avail. He rubbed the sand dollar in his pocket as he wound through the bustling downtown, unsure of where to go. Tyson had slipped it in his hand before ejecting him from Atlantis.

"You can buy your way back home safe with this," he had said.

Percy felt exhausted, in every sense of the word. He hadn't eaten much over the last couple of days, but he didn't feel hungry. Just empty. His eyes burned, his heavy eyelids threatening to overtake them at any moment. On the outside, his chest burned as well, the wound chafing against the fabric of his shirt, and on the inside, his chest felt heavy, as if his organs had turned to bricks. Passing by an old, ornate cathedral, he saw a sign with huge, English words and struggled to make them out. Pushing through the word soup, he finally read: St. Petersburg Church of the Saviour. Judging by the crowd, it must have been a popular tourist destination. Percy accidentally locked eyes with a tour guide, and he could have sworn that when the woman licked her lips, her tongue was forked, but he didn't pause to be sure.

He let his feet take him on autopilot, roaming deeper and deeper into the city. He wasn't sure where they were taking him, but they seemed to navigate with a mind of their own, as if his body were being called to something or someone. His mind was too tired to question it.

His feet were screaming by the time he heard those familiar mutterings again. Fighting his tired limbs, he picked up the pace, the noise getting louder.

Warlord! she exclaimed.

He paused at the base of a bridge over a canal. There was a walkway along the side of the canal that passed under the bridge, and he dropped himself down to it. Huddling under the bridge was Anastasia, hugging her knees to her chest. She turned to look at him, dejected but relieved at the same time.

"Surprised to see me?" he asked.

"No," she lied.

He sat down beside her under the bridge, leaving as much space as possible between them. He felt a connection to her, and he knew he had to do right by her, but he also didn't really want to be near her that much. He felt her mean, bitter energy again, and he had too much of his own now to handle it. She wasn't offended, though; the feeling was mutual.

"What are you doing here?" he said.

She crushed a leaf on the ground between her fingers. "The Fates did not interfere with this part of my father's punishment," she said. "He wanted to kick me out to the mortal realm. They obliged."

He nodded. "Okay." He looked down at the canal and saw a couple of faces staring curiously up at him. He turned back to Anastasia. "Can you leave?"

She shrugged. "It is not like my father is still around to enforce my banishment, but the journey back through the sea would still be treacherous. I am not sure it is worth it. I was thinking I would just stay here." She looked up past him, toward the city. She knew this place inside and out, he realized. She had lived here before.

He shook his head. "No way," he argued. "I'm supposed to help you. We were given instructions by the Fates. I can't help you if you're all the way in Russia."

She shrugged again, and he wasn't sure if the empty feeling that surrounded them came from her or himself. He gritted his teeth. They couldn't both wallow in hopelessness. Someone had to take charge; he guessed it had to be him.

"Come on," he urged, "what did the Fates say? 'Keep your path' or something?" He was frustrated at how little he remembered of their exact wording already.

"'Keep your word to prove your worth,'" she corrected, mimicking the Fate's voice perfectly. He could tell that she remembered every single word they had said exactly as they had said it.

"Whoa," he muttered.

"It's a psychological fact," she explained monotonously, "those who cannot read have better memories."

He blinked in surprise. It had never occurred to him that Anastasia had never learned to read. She seemed sensitive about that, though, so he glided past it. "Alright, cool. So, at least one of us has that down."

She looked up at him, her face hard, and frowned. "Even if we safely made it through the sea," she said, "what would I do in New York? Just live in your bedroom?"

He grimaced. "Gods, no," he blurted, then caught himself. "I mean, we'd figure out something better. Plus, you can disguise yourself as anybody."

"Not twenty-four/seven," she countered.

"Yeah," he said, "but it's better to get you out of here in case your father comes back." He searched her mind, but she didn't know what had become of him either. "I don't know what the Fates did to him, but if he came back once, he could potentially do it again. This is the first place he'd look for you."

She sighed bitterly. "I suppose that is true."

"You'd be safer the further you can get from here."

Her lip curled. "What is the point if I am just going to die anyway," she said, and he found it difficult to argue.

"It's…I don't know," he said, searching for words. "Look, it sucks. Like they told you before you met me, your existence is cursed. You shouldn't exist, and neither should I. And I'm supposed to help you pass from this painful existence into a freer one. Now we finally know what that means." She rested her forehead on her knees, closing her eyes. Swallowing, he continued, "If we do this right, you get to be reborn. A guaranteed second chance at life. A better life." He waited as the wheels turned in her head. He watched the ripple of the canal, gazing at the frigid water. Two naiads watched back, just below the surface. He nodded at them. They whispered to each other but did not smile.

Finally, she lifted her head and sighed once more. "I guess it is worth a shot," she said. "I might as well do what the Fates want. They are always going to win in the end, anyway."

"That's the spirit," Percy deadpanned, standing wearily. She stood too.

Looking down at the naiads, Percy waved. "Um, hey, guys," he said awkwardly. "Can you help us get out of here?"

They whispered to each other again.

"Um, please?" he said, pulling out the sand dollar.

Their eyes grew wide, and they disappeared. Moments later, a blue-skinned man with a hammerhead shark head and crab claws for hands crawled out of the canal onto the walkway in front of them.

"I understand you want ticket out of here," said the river god in a thick Russian accent, like Anastasia's. He held out his claw expectantly.

"Discreetly," Percy said.

Soon, the two of them were plugging away across the Atlantic in a simple sailboat. All of the boat's mechanisms responded to Percy's mind, and he rested on the deck while Anastasia sulked below, as far from him as possible. Her thoughts were quieter to him now, and he was able to tune out the noise.

The sailboat travelled impossibly fast, but it still took almost twenty-four hours to cross the expanse of the ocean. Despite his tiredness, Percy awoke several times in the night, jolted out of his nightmares of being burned and electrocuted. Sometimes he was himself, sometimes he was Anastasia. Sometimes he felt her presence in his dreams, sometimes he was alone. He hated having her nearby while he slept.

They finally approached New York City, the Statue of Liberty looming in the distance. Realizing he didn't want them to be stopped by the coast guard, he bade the ship to come to a halt while they were still a ways out.

Stomping his foot on the deck, he shouted, "Land, ho!"

Grumbling, Anastasia emerged from below. "What now?" she said grumpily.

Looking over the edge of the boat, he considered what to do. Pulling his arms out of his sleeves, he took a deep breath, then jumped over the side, removing his shirt cleanly as he did so and stuffing it in his back pocket. She hesitated, then jumped in behind him.

Percy patted the side of the ship, and it turned around and raced back out to sea at blinding speed. Anastasia was staring at Percy's chest, which really pissed him off. Instantly, she averted her gaze. Huffing, Percy grabbed Anastasia's wrist and, concentrating, willed them to Calli's cove. Melting into water, the two of them raced around the Long Island Sound with the currents until they surfaced in the same place they had left from, Percy scrambling to pull his shirt back on and lying on his back on the shore.

I can already tell this is going to get annoying, he thought. Anastasia side-eyed him, clearly curious as to what exactly had happened to him but knowing better than to ask. He didn't explain.

She thought about calling for Calli, and then, thinking better of it, merely sat by his side while he fought his exhaustion. She really wasn't kidding; travelling that way was draining. He lied there until the sun started to sink again. Sitting up, he looked across the Sound at the Bronx glumly. He was so close to home, but he knew they had to come up with a plan for Anastasia before he could get there.

He was distracted from his musings by Calli's voice.

"Percy!" she called, manifesting out of the water ahead of him. She threw herself into his arms, forcing him down on his back again. Embarrassed and groaning, he pushed himself back up, but she didn't let go of him.

"I was so worried about you," she said. "I heard a rumor that you…that your father…"

"What?" Percy said, upset. "How?"

She let go of him and sat down in front of them, twisting a strand of her hair in her fingers. "Rumors travel pretty fast in the sea," she said. "People just like to talk."

"Yeah, I've noticed," he griped.

"What happened?" she asked, looking back and forth from him to Anastasia.

Percy opened his mouth, then closed it again. What could he tell her? He felt all of his overlapping oaths binding him like ropes around his wrists. He couldn't say what his father had done to him, and he couldn't tell her why he couldn't tell her.

Noticing he was at a loss for words, Anastasia stepped in. "We went to the Sea of Monsters to speak to my mother," she began, and Percy realized that so much had happened over a very small amount of time. Jumping in, he relayed their whole journey to the Sea of Monsters to Calli, sparing no details. She listened in worry as he recounted what the Sirens said about their fathers and gasped in horror when he told her how Oceanus planned to use monsters to punish mortals if he got the chance. He told her about Ketos and concluded with being whisked away to his father's kingdom.

He stared at the water thoughtfully, leaning back to rest on his elbows. "I don't know what you've heard happened there, but it's probably true," he said.

"Each of our fathers believed we had betrayed them for one another," Anastasia explained. "We figured that the only way to get them to pity us and spare our lives was to pretend that we had fallen in love with each other."

Calli appeared crestfallen. She turned to Percy and asked hoarsely, "Is that true?"

Percy felt a twinge of guilt, though he was not sure why. He just hated seeing Calli sad. "Yes, it's true," he said. "We had to lie. They believed the lie, and it saved our lives. Well, mine."

Anastasia was starting to put the pieces together through all the glimpses into his mind. "His father convicted him of treason anyway," she said. "And punished him."

Calli's eyes grew wide. "Treason?" she exclaimed. "Percy, you're not a traitor!"

"I know," he said. "It was a stupid technicality. But really, I just think the gods wanted me to suffer." He scowled bitterly at the ground, watching the waves lap at where his elbows were resting.

"My father wanted me to suffer too," Anastasia said. "He and his wife cursed us. And…" She looked at Percy, unsure of how much to tell this nereid. Percy knew it was better not to involve her; it was safer for her that way. But he found it so hard to keep things from her.

"The Fates intervened," he said, causing Calli to gasp yet again. "They gave us a mission, basically. So, we're stuck with each other for the time being."

"Oh, Percy," was all Calli could say.

He looked out at the orange sky, wishing he could sleep. "I need to figure out what to do with her," he said, jerking his head toward Anastasia. "I can't be seen with her. We're not supposed to be interacting anymore."

Anastasia didn't like his tone. Crossing her arms, she looked at Calli and said, "Got any ideas?"

Percy shook his head. "No, don't. I don't want you to be accused of treason too, if anyone finds out you know about this."

Calli looked back and forth between the two of them again, as if considering a decision. Then, standing, she said, "Come with me."

She led them along the water around the Great Neck to Little Neck Bay. Percy nervously hoped that the rich people living along the Sound wouldn't get offended at these three teenagers walking through their private property, but they luckily encountered no one. In the bay, Calli motioned for them to follow her underwater. Gritting his teeth, Percy waded up to his waist, then whipped his shirt off and plunged below the surface.

Calli didn't notice at first, but when she turned around to make sure they were still there, she let out a small scream. Underwater, she looked a lot less human and a lot more like the ethereal nereid he had encountered on his first mission way back when, though she was still clearly sick. It dismayed him a little that his appearance disturbed her like this.

Approaching him, she tentatively held out a hand as if to touch the mark, then withdrew it. "Oh, Percy," she said, "I'm so sorry. It is true."

"It's fine," he said, wishing he could die.

She tenderly touched his cheek, then backed away. "I want to show you two something secret. Something abandoned that only I know about."

Percy and Anastasia followed Calli down to the depths of the bay. Anastasia was anxious they would encounter other nereids and water spirits, but Percy allayed her fears. Most of the nymphs and male spirits around Long Island had disappeared or abandoned it long ago, unable to withstand the sickness and pollution that came with it. There were only a few left, and they divided the coastline between them. The only decently clean stretch of beach on this whole island was along Camp Half-Blood, and that was on the other end.

Calli led them to a rocky wall along the edge of the bay, deep below the surface, and stopped. Behind her, Percy and Anastasia shared a dubious look. What was there to see? Calli placed her palm against a crack in the rock and uttered, "Sanctuary of the nymphs, heed my prayer," in ancient Greek. The crack in the rock grew until it formed a crevice barely wide enough for one person to squeeze through. Motioning them to follow, Calli swum inside.

When they emerged through to the other side of the rocky wall, Percy was stunned. Hastily throwing his shirt back on, he emerged into an enormous air-filled cavern that stretched on as far as his eye could see. It was a rocky expanse filled with lakes, sandy shores, and seagrass. A few rays of sunlight seeped through cracks in the ceiling here and there, and fruit-bearing trees grew under those rays. In the distance, in the middle of the cavern, what looked like a large, lush oasis sprang forth. He and Anastasia stared in wonder, slack-jawed, taking it all in. It was beautiful.

"Welcome," Calli declared, "to the Cave of the Nymphs."

According to Calli, Melissani Cave, also known as the Cave of the Nymphs, was a secret oasis for those who needed sanctuary by the sea. It was filled with gorgeous, sparkling lakes, some saltwater and some fresh, and it stretched the entire length of Long Island.

"There's even an opening near Camp Half-Blood," she said.

Percy could hardly believe it. "So, who knows about this?" he asked.

She shook her head. "Like I said, it's only me. This cave only presents itself to people who have need of it. People who need an escape."

Anastasia gazed out at its expanse. "But it is massive. How do you know no one else is down here?"

Calli scowled at her. "There might be other people down here, but you won't run into them unless you're looking for them. This cave is shrouded in secrecy to protect the people who find it. If you come here, you'll perceive yourself to be alone unless you specifically search for someone you know to be here."

Percy and Anastasia locked eyes. It seemed too good to be true.

Percy walked up to Calli and whispered, "Calli, I can't let you do this. I can't take this space from you."

She shook her head. "It's fine, Percy. I can still be alone here if I want to be."

He grabbed her hand. "I don't want you to get in trouble for helping me."

She gave a soft smile. "Don't worry about it," she said. "I know you'd do the same for me."

He suddenly got an idea. "I'll make it up to you," he promised. "If you keep our secret, I'll figure out a way to clean up the Long Island Sound."

She laughed, as if that were ridiculous, then choked it back. "Okay, Percy," she said, amused.

"I will. I swear." He looked into her eyes with fierce determination. "You shouldn't have to live in these conditions," he said. "It's not safe, or healthy, or right. I'm going to do something about it."

Her eyes shone, and she squeezed his hand, which made him feel like he was doing the right thing. Even Anastasia seemed impressed in spite of herself.

"Well," the demi-titan said with a shrug, "I had better get comfortable. Come back and see me soon, but not too soon, dog."

He rolled his eyes and left with Calli clinging affectionately to his arm. She went with him as far as the edge of the East River, then left him with a kiss on the cheek. He put on his shirt as he waded into the freshwater, then, gathering all his energy, he melted into the river and zipped along the Manhattan coast.

It was already dark when he got home, so he decided to sneak up the fire escape into his bedroom. He was out like a light as soon as his head hit the pillow. The next thing he knew, he was awakened by a knock on his bedroom door.

"Percy?" his mom said softly, then cracked his door open. "Oh, Percy, thank the gods you're back!" she cried, hurrying inside and stroking his hair. "It's time to get up, okay? You don't want to be late for your first day of school."

Kill me, Percy thought with a groan.