When Chase Sanders left for college, he had dropped a kiss on his mother's cheek and promised to study hard. He tried to keep his promise - tried for nearly three years. But when he hit 21 and began to realize that time was slipping past him, the promise was gone. Every night was the same for the boy afterwards - party with his new friends until 2 am, miss almost all of his classes because he was so hungover, and then repeat. At one of these parties, he met Rita Walsh and by the end of the night, the two had become close. However, while Rita saw them as an exclusive couple, Chase saw them as nothing more than friend with benefits. After all, he was too busy living and being young to be caught up in a serious relationship.
His longing to stay young forever is what attracted Hebe to him, and the two met one night during a party, with Hebe introducing herself as Haley. The two hit it off right away and later left the party together, the night ending with a one night stand.
Only a few months later, Chase heard a knock on his door and when he opened it, he found a newborn in a wicker basket. There was a note that had been left pinned to the blanket that explained that the baby was his. Chase was shocked and Rita was heartbroken that her boyfriend has been unfaithful, but she had always been too forgiving and she explained that she would help raise the boy with Chase.
However, Chase wanted nothing to do with the baby, stating that he wasn't ready to be a father and that they should just give him up. Rita, not wanting the baby to be left in foster care for years, left Chase and formally adopted the baby boy - who she named Mathias after her great-grandfather. Chase never tried to contact either of them afterwards, seemingly content with his life.
Despite having no blood relations to Matt, she treated him like her own son, spoiling him as much as she could. Matt had just turned two, Rita moved from Colorado to New York to be closer to her parents. There, she met Micah Grey and fell in love once more. Micah's presence wasn't only good for Rita - it was also good for Matt, who saw the man as a father figure. When Matt was five, the two got married and Matt took his step father's last name. A year later, they welcomed their first child together: Olivia.
It was around this time that Matt began complaining of nightmares and of monsters chasing him in the middle of the night. Micah and Rita worried this was a sign of them spending too much time with Olivia and of Matt needing more attention. Slowly the complaints went away, but sometimes, when Matt walked to school, he'd see odd things following him. He'd never tell his parents - thinking that they were nothing but his imagination. He'd leave the tall tales to his younger siblings.
Once he began middle school, he met Liam Thorn, a boy who was almost always on crutches and complaining of a strained ankle. The two were close friends throughout the years, but after Matt's 13th birthday, he noticed how anxious Liam always looked. Originally Matt thought he was just being his worry wart self, but whenever he questioned it, the other boy would get defensive and snap, so he knew something was wrong. But just because he didn't question him further didn't meant he forgot about it - especially as his 14th birthday drew closer and closer, and Liam fidgeted more and more.
Despite his constant worrying over everything, Liam seemed rather calm around Matt's neighbor, a cranky lady in her 40's named Mrs. Sexton that only seemed to enjoy her soap operas and watching the two boys. The older woman made Matt uncomfortable - but Liam always claimed they could trust her.
While Liam was over at his house for his birthday party, a harpy attacked the two boys. clawing and scratching at them and trying to pick them up. To Matt's confusion, Liam didn't run to the Grey house, instead he ran to Mrs. Sexton's home. Mrs. Sexton answered the door and when she saw the harpy flying towards them, she took off her necklace, which changed into a sword before their very eyes, and attacked the monster, killing it after a short fight. Mrs. Sexton grabbed the two boys, almost dragging them towards her car, before Matt protested, insisting on knowing what was happening. They didn't tell him anything, instead Mrs. Sexton gave the younger boy permission to leave a note to his mother, telling her he was fine and was with them.
As they drove, Liam explained what had happened quickly and quietly, like he was afraid of being heard by someone else. He told him that he (Matt) and Mrs. Sexton were demigods - with Mrs. Sexton being a daughter of Nemesis - and that he was a satyr sent to find demigods and bring them to Camp. He also explained that as a demigod, monsters were just itching to rip him to shreds and that he may have survived a harpy attack alive but he may not next time. Matt didn't believe him at first, angrily asking Liam for proof. His proof was him pulling his pants down and revealing his goat legs.
Matt was in shock the whole drive there and the whole sprint up the large hill. At first Matt thought it was his real father that had been the god, as he never knew the man. But a few days after arriving at camp, a symbol appeared over his head - claiming him as the son of Hebe. Matt didn't want to believe it. He struggled with the idea of Rita not being his real mother, having new siblings he never even knew about, and that he had never even meet his real parents and would probably never meet them.
He spent two weeks at the camp before going home, knowing that he would have to face Rita about it at some point. While Rita fussed over him when he came home, she soon realized that he was acting strangely distant. When Matt explained that he knew the truth, Rita broke down, apologizing for not telling him sooner. Matt also explained that he was a demigod, that his real mother was a goddess and while Rita didn't believe him at first, she slowly began to.
He left a few days later, but not after Rita stopped him and told him that despite her being his adoptive mother, she loved him like he was her own - a fact that made Matt feel better.
While it did make him feel better about himself, secretly, he felt out of place.
Matt tried to evenly spilt his time between his home and the camp, and ended up spending two years at camp before his youngest sister, Daisy, was born in 2009. He left camp after her birth to help Rita and Micah take care of the other children. He originally planned to stay for a week and then return to camp but after the week had gone and passed, he had become used to being at home and didn't want to go back.
Instead, he stayed with his family and went to school like a normal child his age, though he was far from normal. He still felt out of place at home, knowing that none of them were his biological family, but also because he was a demigod, meaning monsters had the tendency to try and kill him. Luckily, because he was the son of a minor goddess, monsters didn't attack very often - usually every few months - and the monsters that attacked him were simple creatures.
Matt graduated from high school in 2011 and began attending a community college shortly after. He thought of returning to camp, but never planned to. However, in 2015, while watching his younger siblings play outside, he was attacked by a hellhound and, even if he managed to kill it before it hurt his family, he was still cut by its claws, leaving a scar along his ribcage.
He then realized that by staying with his family so much, he was just putting them in more danger and left home for Camp Half-Blood.