Belenos was trying to do some research on a new drug using human ways in a medical facility. There he met a paramedic named Elly Steele, and he got attracted to her, and so did she to him.
They got so close together that they started sharing bed together. Unfortunately Belenos finished his research and he needed to go back to his realm, so he left Elly even before Elly herself found out that she was pregnant.
Nine moths after Belenos left, Elly gave birth to a boy that she named Jayson Steele. Jayson grew up to be a healthy boy, although he had to deal with ADHD - as is common to happen among demigods.
the only real bad thing that happened to Jayson and Elly was when JAyson was 10 years old, Elly contacted tuberculosis from one of her patients, and she had to undergo treatment for her illness. Unfortunately, because of her busy life Elly couldn't keep up with the rigid treatment and the virus that she contracted became resistant to medicines. In other words, Elly was dying.
Another bad thing happened while Jayson was at the age of twelve, when he got his first attack from a monster, but a satyr saved him. The satyr then explained to Jayson and Elly about Jayson's real identity as a demigod and also about Camp Mythology where children like Jayson can stay and be safe.
Jayson refused to go the camp, because he felt that he couldn't leave his mom in sick condition. The satyr understood and he left, but not before giving Jayson his business card and a sword. That sword was originally a gift from Belenos for Jayson, but Belenos made the satyr promised not to tell Jayson about it.
Three years later Elly finally succumbed to her illness and died, leaving Jayson practically alone. Realizing that he might be put into foster care, Jayson made the decision to call the satyr back and asked the satyr to escort him to Camp Mythology. After he got there, Belenos finally formally claimed Jayson as his son, and Jayson had been living in the camp ever since.