Percy thought that this would be the calmest summer since he had discovered he was a demigod. Thalia had chosen Artemis, donned silver, and vanished from the game of the prophecy. For the first time, Percy felt the weight of destiny rest solely on his own shoulders—and, strangely, it soothed him. There was no rivalry. No comparison. He was the son of Poseidon, the only one of the Big Three of the right age. The inevitable hero.

And then, damn it, she arrived.

They brought her to Camp Half-Blood on a stifling dawn, carried by satyrs in a panic. She was covered in cuts, her breathing shallow, her eyes far too open for someone on the brink of unconsciousness. She murmured about voices guiding her, about shadows pushing her forward when her legs could no longer obey. No one knew who her father or mother was. They only knew that monsters had been chasing her for days—enough to confirm it: a demigod.

She survived three days.

When she died, the shock was absolute. Even with the war against Kronos looming, the Camp never grew used to loss. They prepared the body in silence, a low, respectful pyre. Percy watched from a distance, with that strange guilt that always came when someone fell in their world. Then the symbol appeared—a black helm wrapped in shadows, hovering over the motionless body. The air froze. The earth trembled. And she breathed.

Daughter of Hades.

Until then, they said that no child of the god of the Underworld survived birth. The legend was wrong.

And she was Percy’s age.

From that day on, everything changed. The Hades cabin was raised in haste, isolated. She slept alone. Ate alone. Trained alone. Percy watched her from afar as he mastered the water with greater precision, feeling the sea respond like a newly discovered muscle. She, in turn, split the ground beneath her opponents’ feet, summoned shadows that clung to ankles, won games and contests that had once belonged to him—and, occasionally, to Clarisse.

She did not possess the predictable beauty that the daughters of Aphrodite had. She was worse. There was something about her that hypnotized and repelled, like staring straight into an abyss. Percy noticed the general discomfort. He also noticed that she seemed averse to everyone—and especially to him.

The tension grew silently, like a tide before the storm.

On the night of the great summer bonfire, when stories were told and the smell of smoke mingled with the salt in the air, Percy saw her slip away. He followed her to the beach. She was sitting on the sand, facing the dark sea.

He cleared his throat, rehearsing lightness where there was only alertness.

“You know… this beach is kind of mine.”

He waited. No visible reaction.

“I mean, literally. Son of Poseidon.” A crooked half-smile. “It’s not just a figure of speech.”

The sea stirred behind her, as if answering the provocation. Percy felt the water vibrate; he also felt the earth beneath his feet—solid, ancient, watching.

He crossed his arms. “I just wanted to understand you. Or maybe make sure that… you’re not here to take my place.”

The wind carried the scent of the Underworld for an instant. Percy kept his eyes on her, aware that that camp season would not be remembered for calm—but for the silent beginning of a rivalry between sea and death.