Sean's mother, Nancy is an Irish immigrant who moved to the states. Her original name was Nainsí, but she changed it to the English version of Nancy to fit in better. She started work as a day care employee in Boston. It was then that she caught the eye of a particular sea god living up on Olympus. Poseidon really admired the way she cared for all children and how loving she was towards the day care kids. So he went down to Boston and posed as a single dad looking to send his kid to the day care. The two got to talking which lead to a date, then two then three... finally on the fourth date, the two hooked up and Nancy became pregnant with a son. Poseidon was forced to leave at that point, so he made up some pretense that through legal action, his ex was forcing him to move.
Nine months later, Nancy gave birth to a baby boy whom she named Sean. For the first year and a half of Sean's life, it was just the two of them. Then Nancy started seeing a guy who worked for the Navy as a pilot. One thing led to another, and about nine months after they started dating, they were married. Now Sean had a father figure to look up to, and a damn good one at that. His name was Jon Smith, and he treated Sean like he was his own son. Something Sean still greatly admires about his dad.
About three years after Sean was born, Nancy had another child, a girl this time named Joanna. With Jon of course as the father. Two years after that, the couple had another child named Mary. For a while the family seemed perfect, and they were. Until Seans's 11th birthday that is.
The family was celebrating by having a nice picnic when out of the nowhere, a great big black dog charged up the hill and pounced onto Sean's chest. Acting on impulse, Sean threw the dog backwards into a tree. The impact of which broke the remaining strands holding a very sharp widow maker in place. It not only crushed the dog but speared it, turning it into a pile of dust. However, Sean was bleeding rather badly so they loaded him into the car and brought him to the ER to get stitched up, saying that the dog just ran off after being thrown off Sean.
From that day on, Nancy and Joanna were scared of Sean. Clearly, the dog had been targeting Sean, and Joanna believed that they should have let the dog finish the job. Sean was a safety hazard and she often voiced this opinion. To his face, and while Nancy never openly agreed... her silence was enough. Jon would always put a stop to it, but he wasn't around very much. His job kept him very busy. Either way, those kinds of words can really get to a kid's head. It didn't take long for Sean to believe that he was a safety hazard and dangerous to his family, but he wasn't ready to run away. Yet.
There weren't any more strange attacks for about a year, but the next one did come eventually. And this time, someone other than Sean was hurt during the whole thing. The family was taking a hike through the woods even this huge-as* scorpion came out of nowhere and started attacking Sean again. It scurried towards Sean, but the young man jumped out of the way. Unfortunately, the scorpion accidentally hit Joanna instead, breaking her arm in one of its massive pincers. The scorpion scurried towards Sean again, who was on the edge of a ravine that was about thirty feet high. Remembering what happened last time... Sean rolled out of the way and the scorpion fell down thirty feet, and was unable to get back up to attack the family. The family brought Joanna to the hospital, this time saying that she fell the wrong way. The family said that it was a bear that attacked Joanna... and Sean kept his mouth shut, since saying that it was gSeant scorpion would only make him look crazy.
Now that someone else had gotten hurt on account of Sean, the torment only got worse for the boy. Every day, Joanna would tell Sean that it was his fault her arm was broken and of course, Nancy would say nothing. Jon, as usual, stuck up for Sean but he wasn't there enough. Mary did as well, but Joanna would just tell her to shut up, which usually ended with Sean hitting Joanna, which only got him in more trouble.
Another year passed before the next attack came. It was Mary's seventh birthday and it was ruined by the appearance of horses. Mary, being a four-year-old girl, always wanted a pony, but she didn't want an adult fire-breathing horse bearing down on her party. The horse crashed through the window and took Sean out, sending Mary's cake everywhere. Jon, acting on instinct and using his military training grabbed a rifle, took aim at the horse and fired. Because the bullets weren't celestial bronze it wouldn't kill the horse but it certainly injured it. And multiple bullets got Jon's message across, leading the horse to flee out the way it came, leaving Sean with multiple burns. They took him to the hospital again, claiming his shirt caught fire.
Now Sean was at the point that he was noticing girls, and for the most part they didn't notice Sean. Except for this one really cute redhead girl named Susan... Sean and Susan had been flirting for a while and one thing led to another and she led Sean into the girl's locker room. She lured him in for a kiss before revealing her true form and lunging at his neck. Sean rolled out of the way and she lunged again, crashing into a mirror which shattered. Sean grabbed a piece of it and acting on impulse stabbed it into her neck. Again, it wouldn't kill her but she was severely incapacitated. Sean explained to them that she attacked him first and he was just defending himself. Having no proof to say otherwise... the school believed him and the girl was 'expelled'.
Roughly a year passed with things continuing as they were. The family was walking down a street when the next attack came. This time no one was hurt, but the end result was still different than normal. This huge one-eyed, beefy man came charging straight at Sean who bolted it down the street without a second thought. The cyclops blew past Sean's bewildered family as it gave pursuit to Sean. Sean, acting quickly ran across the straight and the cyclops did as well... until a bus rammed into it at 30 miles an hour, leaving the gSeant one-eyed man dazed and confused. Sean, not wanting to go back home to his abusive sister and mother ran off down the street and away from the accident.
Sean took shelter in an abandoned warehouse that night, he didn't know what would become of him now, but he wasn't ever going back home. The next morning, Sean stowed away on a freight train bound for NYC. He was in a boxcar with a bunch of flour that was probably going to various bakeries in and around the city. When the train arrived at its destination, Sean snuck back off and ran into the city.
Sean lived on the streets, playing himself off as just another homeless boy and giving vague answers when asked where his family was. But it wouldn't last long and Sean knew that which is why he was making plans to escape to a different city when he was attacked again. It was a week or so after his 15th birthday when Sean was attacked again by a pack of harpies. He was in another abandoned warehouse when three harpies broke through a window. Sean, once again acting on instinct grabbed a lead pipe and struck at the head of one of the harpies, knocking it out. He then rolled out of the attack range and struck at another's wings, breaking them instantly. The third flew at Sean, claws extended, and Sean struck it over the head, knocking that one out as well.
Sean quickly ran out of the warehouse fast as his feet could take him only to run into one of the other homeless boys that Sean had talked with on occasion, named Steve. Sean, acting on impulse and wanting to tell someoneabout the attacks told Steve everything. To his surprise, Steve wasn't shocked and completely believed Sean. Then he took his pants and shoes off and revealed goat legs. Steve told Sean he should sit down because he was gonna be confused as hell. Steve, the satyr told Sean everything about Camp Half-Blood and the greek gods, and Sean was good until Steve said that Sean was a demigod. Sean didn't believe him at that point but having nothing else to do... he followed Steve to this supposed camp. He was desperate and honestly, it wasn't the craziest thing that would have ever happened to him. Sean wasn't at camp for more 24 hours when he was claimed by Poseidon, the god of the sea. Sean was just kind of rolling with it... but he wasn't a huge fan of the camp. The only reason he hadn't left was because of one of his half-sisters, Mariana Torres. After like a week at camp, the pair decided that they were going to leave. Mariana knew an older demigod who was willing to train them, the next morning they left camp to train with the older demigod. The next two years were difficult and arduous but at the same time they flew by and now Sean knew how to fight better, and had accepted that he was a son of Poseidon at this point. The attacks just kept coming everything from hellhounds to fire-breathing horses. Eventually, Mariana and Sean agreed to return to camp, so they could live a more normal life. The older demigod, Nathan and a mortal named Chase stayed behind while Mariana, Sean, and Mariana's mom left for Camp Half-Blood.
Before they arrived, they were ambushed by rogue demigods. Sean doesn't care why they ambushed... only the end result of their attack and a pack of hellhounds was the death of Mariana's mom. Sean had to forcefully drag Mariana away from the body and into the camp, the only safe place for them now. That was almost a year ago on December 29, 2016 and Sean has been at camp ever since.