His father was born in New York. He is actually a Roman demigod, the son of Neptune. His mother knew about the danger he might get into with monsters, and she didn't want Ryan to go to Camp Jupiter for the rest of his life. She asked Neptune to create a shield or a spell to protect him from all these danger. Neptune then asked Trivia (Roman Hecate) to secretly cast a protection spell on him. Trivia only did this because Neptune helped her daughter, a demigod, by saving her when she was nearly drowned, so she owed him and she had to cast this spell. Since Trivia is the most powerful Titan/Olympian witch, her spell was very powerful, so powerful that it hid his true identification from all monsters and gods if he never meet or interact with a god or a monster or use his powers to fight against it, it hid his identification from both Greeks and Romans, only Ryan and his parents knew that he's a demigod. Ryan then studied double degree (Architecture and History) at Havard. After graduation, he went to teach at NYU (Architecture and History). After that, he got promoted as the History Department's Dean. At the celebration party, Ryan met a beautiful European lady, who is actually Athena in disguise as Penelope Botman. They went out for 7 months, and then Justin came along. Although Athena didn't know about Ryan's demigod identification, Ryan did know that it was Athena in disguise. After Justin was born, Athena stayed for 2 months, and one day, she disappeared, left only one note, said: "Dear Ryan, I have to go back to Olympus now. I wish you will live happily. Take good care of Justin, please. I shall see you and Justin someday in the future. Goodbye!". Ryan then raised Justin all by himself. Although he was offered to teach at Havard and Yale, he wanted Justin to study in New York, in order to be near to Athena.
Justin had quite a normal childhood. He's always a good student, loves to read books and always has good grades, unlike most of demigods who have big trouble at school with their ADHD and dyslexia. At a very young age, Justin showed talent in leadership, strategy making and studying. He knows a lot about everything, and had a good memory.
When Justin was 12, he went to a middle school in New York named Karollen Academy. That's where he met his best friend Samuel Gretty, who is actually a satyr. After meeting Samuel, the signs that prooves Justin is a demigod started to appear. The owls in his neighborhood stared at him all the time, he heard the sound of the owls talking to each other, he's more afraid of spiders than ever, he suddenly knew a lot about Greek mythology without reading books about it, he remembered everything he reads, he could translate things to Greek, read and speak Greek fluently.
His first monster attack was when he was 13, when he was walking in the park at night in the Central Park. His dad was in Seattle, his grandma who was in charge of taking care of him was sleeping, he felt like walking in the park, so he called Samuel and the two hang out in the park. It was winter, and there's no one in the park left. Suddenly, the two heard a strange sound. Came out from the trees was a humanoid female with twin serpent trunks instead of legs. Her walk was a combination of walking and slithering like walking on living skis. She was wearing an armor and she held in her hand a big spears. She started to attack Justin and Samuel. The spear almost touched him. Justin then picked a nearby sharp branch and stabbed her in the human part. She yelled and when she was about to attack Justin, Samuel threw Justin a dagger and he used it to stabbed her, made her vaporized. After that, he didn't remember a thing and woke up in his bed next morning. When he asked Samuel, he said he didn't know anything about the event, made Justin belive that he was dreaming all along. Then five months after his first monster attack, he, Samuel and his father went to the Museum of History for a weekend trip. When they came there, they went to a section that was being rebuilt. Suddenly, the earth was shaken and an unfinished 10-feet sculpture of a typical ancient Greek soldier fell down. Justin was so frightened, he instinctively defended himself by holding up his hands, and all the loose rocks around him automically came together and weave a big defensive wall, made the sculpture broke down. After saw what was happening, they immediately took Justin out of there and back to their home. Justin freaked out and asked his dad for an explanation. His dad finally told him the truth that he was a demigod, the son of Athena, but he still hid from Justin the fact that Ryan was son of the Roman god - Neptune.
A year after found out about his god mother, Justin had his second monster attack. He was in the gym alone, practicing basketball when he saw a huge black dog appear out of nowhere. He had very long sharp teeth, his eyes were full of evil, he make the whole atmosphere around him became colder and creepier. He remembered read about this species in mythology books, this species is called Hellhound. He still had a back-up dagger in his pocket that his dad gave to him just in case. He tried to attack him from behind, but it didn't work perfectly. Then, Justin jump on a fake cliff that his school created for the sport festival. The cliff was narrow, and when the hellhound jumped on it, it started to get offbalance, and Justin quickly stabbed him, destroyed the monster. He rushed back to his house where he saw his dad and Samuel talking. Justin told everything to them, and Samuel confessed about the first monster attack, that it was true, not a dream. After listened to this, his father then revealed that he knew Samuel was a satyr, and asked Samuel to take Justin to Camp Half-Blood. Ryan, Justin and Samuel then caught a bus to Long Island. 1 hour later, they arrived at Long Island. They walked to the camp, but when they started to go into the woods, they saw a huge black horse. But this horse is nothing like the normal ones you see at barns. At first, they thought it was a normal horse, but its mane is on fire, it had circlets of fire around its hooves, and its tales are on fire. When the horse openend its mouth, fire came out of it. Samuel whispered to Justin: "It's a fire-breathing horse. Be careful". The horse started to run towards them. They ran and ran, until they met a cliff. Realized it was time to tell his son the truth, Justin's father started to concentrate on his hands, think about the blue and powerful oceans, and than do exactly what his son did back in the museum. Suddenly, water from a near-by lake started to move towards the horse and follow the directions of Justin's hand, made the horse weaker and weaker, until it automically vaporized. Wanted an explanation, Justin asked his father about this, but the only answer he got was: "I'm the son of Neptune, the Roman Poseidon, which makes me a demigod, and that makes you Neptune's grandson or his legacy, although you don't have water powers. Look, give this paper to your camp leader, he'll tell you more about this. I've got to go now, if I don't leave now, more monsters will arrive. Before you leave, I give you this powerful sword that your mother gave me to give it to you someday. When you don't use it, it and the dagger I gave you, which is also your mother's, will turn into a watch. You can put other weapons in it. When you need it, just click these buttons. Goodbye and good luck my son". His father then turned into water and disappeared. Justin and Samuel came to the camp, but the forest was too big and wide, and Samuel's guide necklace was broken. When they were trying to find the way to camp, a flying owl out of nowhere flew down to him, landed on his hand and give him a scroll along with a necklace. In the scroll, there was a message written in Greek, but Justin can read it, and it said: "This owl will lead you to the camp, and I hope you will arrive at the camp safely. When you got there, the necklace will glow. Hope you will always be safe, brave, smart and powerful. Good luck, my son". They walk and they walk, and finally the necklace glow, and in front of them was Camp Half-Blood. They walk through the gate, and now his demigod adventure will begin.