Everything you've ever known about Harry Potter or Percy Jackson: you might as well erase it from your minds right now. Because while some of the characters are the same this will be their stories re-written in a very new way.
He lay in their observatory, under the stars. Beside him lay one of his favorite books on Greek Mythology. According to his father, those myths were actually a very real reality. The boy was excited at the prospect of the God's and Goddess's existing. Oddly, he was more excited about the Demi-God's, and hoped to one day meet one. As this thought crossed his mind, he heard his father's voice travel up the stairs "Cedric" and he vanished in a flash of light.
The little satyr lay down in his bed in the Poseidon Cabin. He would stay here until he was old enough to be sent to go find the only living son of Poseidon and protect him. Some days he found the training and lectures boring. But other days he was glad that this was his destiny; there are so many worse things he could have to do. He heard the four tell-tale hoof steps that signified Chiron coming to check on him. Just as the centaur said "Grover" he faded away with a bright flash of light.
She lay at her mothers' side as she listened to her stories about her experiments and her new ideas. Her mother brushed her hand through her long blonde hair and sighed, "Luna, I love you very much, and so does your mother." The little girl looked up at her 'mother' just before she disappeared in a bright flash of light.
The little boy sat dejectedly in a corner, staring at the picture in his hands. The picture was of him and his parents, before they had gone mad. He could only barely remember a time before he lived with his grandmother. A time before he was yelled and picked at all the time. He heard his grandmother yell "Neville" and then he was gone in a flash of light.
A small girl raced away from her father, giggling as he chased her through the house. They had been playing a fun game of hide and seek before bedtime, and when she had found him, he had begun to chase her. "Daddy! This isn't how you play hide and seek!" She screeched as she turned a corner and ran straight into his arms. "My little Thalia Star, you can make up the rules to any game." And as the little girl smiled she vanished in a flash of light.
He stood behind his twin sister and watched as their parents showered her with attention. He was the least favorite; the one they always ignored. The child couldn't really understand why his parents didn't love him. As he began to move away and head to his room, his mother called to him smiling, "Nico, come here," and as he turned, he was gone in a bright flash of light.
She sat in her bed. She could hear her father's snoring from the room next to hers. He was always so tired at night. He never had any time to play with her. But he always made it a point to tell her a bedtime story. Tonight's had been about the half human, half God children called Demi-Gods. Just as the little girl was about to turn over to go to sleep she heard her mother stick her head in through the door, "Goodnight Annabeth," and before the girl could open her mouth, she disappeared in a flash of light.
A little girl cowered in her room as she listened to her parents screaming at each other. She listened as glass smashed against the wall, bursting into pieces. She listened to her mother sobbing and her father slamming doors. The last thing she heard was the door open and her parents yell "Hermione" as she disappeared in a flash of light.
The little boy cowered in his small bedroom, covering the place on his cheek where his father had just slapped him. All he had wanted was a small piece of his twin brother's birthday cake. It was his birthday as well, was it not? But when he had asked his father had laughed and slapped him. The boy decided he had had enough of it. If they only wanted Daniel as a child, that was all they would have. So he began to pack a bag, putting a small amount of clothing, a few books, and all the money he had saved up. He put the small bag on his back and turned when the door opened, and there stood his mother, "Where are you going Harry?" With those words, he vanished in a bright flash of light.
He sat in his bed, nursing the swollen ankle he had received after he tripped trying to get away from Gabe. The man had hit him repeatedly, and nothing his mother did could stop him. Finally the man had run out of energy and literally kicked him out of the room. The boy wished for nothing more than the power to hurt the man the way he hurt him and his mother. But as he was only five, he didn't have that kind of power. He removed the ice pack from his ankle as his mother came into his room, "I'm sorry, Percy." The boy had no time to respond as he was gone in a flash of light.
All ten children appeared in an enormous golden hall. Each child turned around in circles trying to figure out where they were. Once they had turned a full 360 degrees, they came face to face with a group of men and women, who smiled fondly down at them.
Percy stumbled a little bit in shock, and Harry helped him regain his balance, though his hand remained on Percy's shoulder.
"Hello, and welcome to κάστρο χάος" the largest man, with golden blonde hair said.