Swirling over Tyson was a glowing green trident—the same symbol that had appeared above me the day Poseidon had claimed me as his son.

There was a moment of awed silence.

Being claimed was a rare event. Some campers waited in vain for it their whole lives. When I'd been claimed by Poseidon last summer, everyone had reverently knelt. But now, they followed Tantalus's lead, and Tantalus roared with laughter. "Well! I think we know where to put the beast now. By the gods, I can see the family resemblance!"

Everybody laughed except Annabeth and a few of my other friends.

Tyson didn't seem to notice. He was too mystified, trying to swat the glowing trident that was now fading over his head. He was too innocent to understand how much they were making fun of him, how cruel people were.

But I got it.

I had a new cabin mate. I had a monster for a half-brother.

The next few days were torture, just like Tantalus wanted.

First there was Tyson moving into the Poseidon cabin, giggling to himself every fifteen seconds and saying, "Percy is my brother?" like he'd just won the lottery.

"Aw, Tyson," I'd say. "It's not that simple."

But there was no explaining it to him. He was in heaven. And me… as much as I liked the big guy, I couldn't help feeling embarrassed. Ashamed. There, I said it.

My father, the all-powerful Poseidon, had gotten moony-eyed for some nature spirit, and Tyson had been the result. I mean, I'd read the myths about Cyclopes. I even remembered that they were often Poseidon's children. But I'd never really processed that this made them my… family. Until I had Tyson living with me in the next bunk.

And then there were the comments from the other campers. Suddenly, I wasn't Percy Jackson, the cool guy who'd retrieved Zeus's lightning bolt last summer. Now I was Percy Jackson, the poor schmuck with the ugly monster for a brother.

"He's not my real brother!" I protested whenever Tyson wasn't around. "He's more like a half-brother on the monstrous side of the family. Like… a half-brother twice removed, or something."

Nobody bought it.

I admit—I was angry at my dad. I felt like being his son was now a joke.

Annabeth tried to make me feel better. She suggested we team up for the chariot race to take our minds off our problems. Don't get me wrong—we both hated Tantalus and we were worried sick about camp—but we didn't know what to do about it. Until we could come up with some brilliant plan to save Thalia's tree, we figured we might as well go along with the races. After all, Annabeth's mom, Athena, had invented the chariot, and my dad had created horses. Together we would own that track.

One morning Annabeth and I were sitting by the canoe lake sketching chariot designs when some jokers from Aphrodite's cabin walked by and asked me if I needed to borrow some eyeliner for my eye… "Oh sorry, eyes.”

As they walked away laughing, Annabeth grumbled, "Just ignore them, Percy. It isn't your fault you have a monster for a brother."

"He's not my brother!" I snapped. "And he's not a monster, either!"

Annabeth raised her eyebrows. "Hey, don't get mad at me! And technically, he is a monster."

"Well you gave him permission to enter the camp."

"Because it was the only way to save your life! I mean… I'm sorry, Percy, I didn't expect Poseidon to claim him. Cyclopes are the most deceitful, treacherous—"

"He is not! What have you got against Cyclopes, any-way?

Annabeth's ears turned pink. I got the feeling there was something she wasn't telling me—something bad.

"Just forget it," she said. "Now, the axle for this chariot—"

"You're treating him like he's this horrible thing," I said. "He saved my life."

Annabeth threw down her pencil and stood. "Then maybe you should design a chariot with him."

"Maybe I should."

"Fine!"

"Fine!"

She stormed off and left me feeling even worse than before.

The next couple of days, I tried to keep my mind off my problems.

Silena Beauregard, one of the nicer girls from Aphrodite's cabin, gave me my first riding lesson on a pegasus. She explained that there was only one immortal winged horse named Pegasus, who still wandered free somewhere in the skies, but over the eons he'd sired a lot of children, none quite so fast or heroic, but all named after the first and greatest.

Being the son of the sea god, I never liked going into the air. My dad had this rivalry with Zeus, so I tried to stay out of the lord of the sky's domain as much as possible. But riding a winged horse felt different. It didn't make me nearly as nervous as being in an airplane. Maybe that was because my dad had created horses out of sea foam, so the pegasi were sort of… neutral territory. I could understand their thoughts. I wasn't surprised when my pegasus went galloping over the treetops or chased a flock of seagulls into a cloud.

The problem was that Tyson wanted to ride the "chicken ponies," too, but the pegasi got skittish whenever he approached. I told them telepathically that Tyson wouldn't hurt them, but they didn't seem to believe me. That made Tyson cry.

The only person at camp who had no problem with Tyson was Beckendorf from the Hephaestus cabin. The blacksmith god had always worked with Cyclopes in his forges, so Beckendorf took Tyson down to the armory to teach him metalworking. He said he'd have Tyson crafting magic items like a master in no time.

After lunch, I worked out in the arena with Apollo's cabin. Swordplay had always been my strength. People said I was better at it than any camper in the last hundred years, except maybe Luke. People always compared me to Luke.

I thrashed the Apollo guys easily. I should've been testing myself against the Ares and Athena cabins, since they had the best sword fighters, but I didn't get along with Clarisse and her siblings, and after my argument with Annabeth, I just didn't want to see her.

I went to archery class, even though I was terrible at it, and it wasn't the same without Chiron teaching. In arts and crafts, I started a marble bust of Poseidon, but it started looking like Sylvester Stallone, so I ditched it. I scaled the climbing wall in full lava-and-earthquake mode. And in the evenings, I did border patrol. Even though Tantalus had insisted we forget trying to protect the camp, some of the campers had quietly kept it up, working out a schedule during our free times.

I sat at the top of Half-Blood Hill and watched the dryads come and go, singing to the dying pine tree. Satyrs brought their reed pipes and played nature magic songs, and for a while the pine needles seemed to get fuller. The flowers on the hill smelled a little sweeter and the grass looked greener. But as soon as the music stopped, the sickness crept back into the air. The whole hill seemed to be infected, dying from the poison that had sunk into the tree's roots. The longer I sat there, the angrier I got.

Luke had done this. I remembered his sly smile, the dragon-claw scar across his face. He'd pretended to be my friend, and the whole time he'd been Kronos's number-one servant.

I opened the palm of my hand. The scar Luke had given me last summer was fading, but I could still see it—a white asterisk-shaped wound where his pit scorpion had stung me.

I thought about what Luke had told me right before he'd tried to kill me: Good-bye, Percy. There is a new Golden Age coming. You won't be part of it.

At night, I had more dreams of Grover. Sometimes, I just heard snatches of his voice. Once, I heard him say: It's here. Another time: He likes sheep.