She explained her life's story to him. In comparison, his past seemed so boring. He had just lived like a normal mortal (albeit, with more behavioral problems than usual) until he learned about Greek mythology. But she had lived Greek mythology.

Her father, who had been spending the last three thousand years or so in the form of the polar ice caps, had apparently decided to retake his person form and rejoin the world. He knocked up a Siren as he was passing through the Sea of Monsters, and unbeknownst to him, that Siren gave birth to a unique halfling creature with powers of the sea and of Sirens. She grew up in the Sea of Monsters (where she learned English), being taught by her mother that her destiny was to reveal herself to her father when she was older and help him launch an attack on Poseidon for control of the seas. In exchange for providing Oceanus with a powerful soldier, the Sirens hoped that the sea titan would release them from captivity on their island and allow them free range over the world. The thought made Percy shiver.

But she had refused. She hated growing up that way, and she hated her mother for raising her as a weapon instead of a child. When she was seven years old, she fled, traveling North and East in search of her father, hoping that he would love her and accept her as his child. But when she reached his ancient stronghold, which was currently centered near the coast of Russia in the Arctic circle, she was despondent to see the suffering of the inhabitants of the sea that lived there. She grew fearful that her father would try to use her like her mother did. Instead of seeking him, she fled once again–to dry land.

She lived the next several years as if a mortal, disguised among the humans as one of them. She lived in an orphanage at first, but she struggled with schoolwork, having no formal education up to that point and having to learn Russian, and she did not get along well with the other kids. She witnessed a lot of hurt, abuse, and violence, and that made her resolve that violence was the root of all evil. She saw a way out of her situation when a travelling circus came to town, and she ran away to join them, spending the next few years training as an acrobat, being tutored sporadically in basic knowledge, and mostly goofing off. There had been a snake charmer, apparently, that she had really liked there, who treated her as if she were his own daughter. He believed strongly in a philosophy of nonviolence, and she had drunk in his teachings like gospel.

But a few months ago, things had changed. She started having dreams in which she saw a black-haired boy and inexpressible anguish. She saw fighting and war and pain under the sea. She felt that now that she was older and wiser, she was better equipped to meet her father. She even thought that maybe she could convince him not to start a war.

Percy didn't need her to continue to guess how that went.

But she continued, nonetheless. She found her father in his Arctic underwater castle. She revealed that she was his daughter and told him about her mother and her visions. At first, he was wary, and she had feared that he would not want anything to do with her. But when he learned that she had had visions of him waging a war against Percy's father, he took that as a sign that he would continue to gain power and support in the sea until he could match, or even overpower, Poseidon. He then seemed more keen to welcome her as his daughter. But when she refused to take part in a war and pleaded for him to reconsider, he grew irate.

"Well," Percy blurted, "what did you expect?"

Her eyes flashed angrily. He knew it was a dick move, but truly, he felt like she should have seen that coming.

"You do not understand. My father did not take part in the first war between the titans and the gods. He was neutral. He was a pacifist." Percy didn't think that choosing not to take sides in one war made someone a true pacifist, but he bit his tongue. "It was a radical act of pacifism for the time," she insisted. "I thought that perhaps I could convince him to keep that position. But it was in vain. He is now convinced that the titans are strong enough to prevail, and he has been promised sole dominion over all the earth's waters if he can regain the sea. I am afraid he is lost." She seemed so pained to admit that, and Percy couldn't help but empathize with her–literally. She hadn't really known her father at all, but she had built up an idea of him in her head for so long that his refusal to see her side felt like a betrayal. He marveled at the fact that he could understand how she felt. She led a life that was so different from his in every conceivable way, but sitting here in front of him now, she seemed so achingly human. Just a broken child, hungry for her parents' love.

"He tried to force me to do his bidding," she said quietly. "But I am more powerful than he realized, and he is still regaining his corporal essence. I resisted him."

Percy found himself awed. She had resisted a titan and won.

"I do not know if I could have subdued him if I had fought him. But I refuse to use my powers for violence," she said. "And so, he cursed me for my insolence. He cursed me to live the rest of my days without friends, without love, without joy, forced to fear the day that he hunts me down and forces me to fight in his war. I told him I would rather die." She glared into her coffee. "And he knew I would not use violence if he tried to kill me. But he did not."

Percy knew what she was hoping, but he was less optimistic. "Because he wants to use you, still."

"Perhaps. Or perhaps he could not bring himself to kill his own offspring," she said. "Or both."

"I think you might be holding onto–"

"I do not care what you think," she spat. "You know nothing of my life, of my family."

"Jeez, I'm just saying–"

"Well, do not!"

Percy felt his sympathy for her fade into frustration once again. "If you hate me and everything I stand for so much, then what are you doing here?"

"Believe me, I am more upset about it than you."

Doubtful, he thought.

"As I fled my father's territory, I had a vision in a dream where the Fates appeared to me. They told me my fate is linked to the American black-haired boy I saw in my dreams, and that with his help, I could hope to avoid the destiny that my father imagined for me." She gripped her coffee mug tighter. "They told me my life has been cursed from birth–that my existence is a transgression against nature, a product of a forbidden union, and I should not exist." Yet again, something Percy could relate to. "They said he–you–alone can help me pass from this painful existence into one of freedom."

Percy's brow furrowed. "Pass? What does that mean?"

"I do not know," she admitted. "And I do not like that you do not know."

"Sorry," he muttered. "But I guess all that explains my prophecy."

She sighed wearily. "It is not like it matters. You do not know how to help me. I do not know what to do. Our fathers will eventually go to war and will likely cause death and destruction across the whole sea. And my father will come for me eventually. Neither of us will be able to stop him."

"Maybe I can," Percy said. "Maybe my job is to go find him now and defeat him before he becomes powerful enough to start a war. Scatter his essence so far that he'll never be able to come back again."

"No," she said firmly, and Percy's eyebrows raised.

"No?"

"I will not allow you to use violence on my behalf."

Percy stared at her, open-mouthed. "You're kidding."

"You know I am not."

"Listen–Anna…something–"

"Anastasia," she huffed.

"Whatever. Hippie-dippy flower child. This is what I've been training for. This is what I do. I'm supposed to fight titans. If this is my destiny, then neither you or I can stop it–and I think the Fates and the Oracle have been pretty clear that it is my destiny."

"No!" she said, standing up. "I refuse!"

"You can't stop me," he said, rising as well.

"Yes, I can!"

"I thought you don't fight," he sneered.

Her eyes flashed. "I have other ways."

He saw glimpses of those other ways in his mind's eye. He wasn't too keen to experience her Siren powers firsthand. But he knew he had to help her, annoying as she was, and even more than that, he wanted to help his father as well. Even though he hadn't relished the thought of being part of a big, foreboding prophecy that he wasn't even allowed to know the details of, he still felt as if his destiny had been ripped from him with the return of Thalia. Maybe, just maybe, this was his chance to play an important role in the defense of Western civilization yet again. Maybe he could even get his father's attention by defeating his enemy before he had a chance to strike.

"Down, dog," she jeered, her voice dripping with contempt.

"Careful," he growled. "You might have sworn a life of nonviolence, but I haven't."

"Typical. Barbaric. If violence is the only language you know, then make yourself heard, Neanderthal."

His blood boiled. "Enough," he shouted, slamming his fist on the table, then winced in pain. The aluminum bracelet Calli had woven for him out of a can was digging into his flesh.

Anastasia gasped and grabbed her own wrist. They locked eyes, and an understanding passed between them. They both lowered to their seats.

"Some birthday," he muttered, holding a napkin to the bleeding cuts on his forearm and trying to ignore the muttering of the other patrons.

Her arm shot across the table to grab his. He recoiled, both at the action and the thoughts in her head, but he was keenly aware of the strange phenomenon of feeling his skin through her fingers. As they stared at each other, he could only shake his head.

"No way," he whispered.

"It depends. What day is it–fuck."

Percy grimaced. She could sense the date in his mind as soon as he thought of it.

"How do you even have a birthday? Aren't you, like…"

"No, I am not immortal."

"How old?" He dreaded the answer.

"Fourteen."

They each sighed deeply. Percy wrested his arm from her grip and ran a hand through his hair. Twins of fate, he mused, over and over. She squirmed in her seat, picking furiously at her nails, lost in thought. He felt he didn't have the energy to unpack the significance of them being born on the same day, just the cherry on top of this whole perplexing sundae.

He glanced at the clock. "We're obviously not going to figure all of this out tonight," he said finally. "And I really should be getting home. My mother is probably worried about me."

She scowled, torn from her reverie. "You cannot just leave me here. I surfaced in this country this morning. I have nowhere to go, I do not know anyone, I need answers–"

"Fine!" He stood up, throwing some cash on the table. "Just follow me, okay?"

She reluctantly stood up and followed him out of the diner. The waitress seemed relieved to see them leave. As Percy led Anastasia down the busy Manhattan streets toward his mom's apartment, he tried not to think about how much trouble he would get in if they were caught together there, or how annoying it was going to be to have her around.

But it was hard not to when she was thinking the same thing.