Seth is a 6th grade boy who lives at Bethel Woods Orphanage. No mention is made of his parents or life before the orphanage, but the story give the impression that he has been there most of his life. He shares a room with his brother Pete in the south-west corner of the boys dorm.
Neither he nor his brother look to be adopted. At one point Seth wished for parents, but Pete stated "They didn't want us. Why should we want them?" Seth agreed with this sentiment and hasn't shown any issues with the decision since.
After a moment of inspiration, Seth explains to his class his plan for their game and directs them in the construction of the machine.
While all the students at the orphanage are extremely smart, Seth manages to stand even further above them. He is known to be very smart with a very analytical mind. Seth also seems to be a natural born leader. He takes control of his entire class with no issues or challenges to his leadership.
Part of the reason for Seth's intelligence over his peers is explained near the end of the story. Seth is one of the very few people of his kidn in the world that is not affected by Shimmerings.
Seth is very protective of the people close to him. He cares very much about his brother Pete and worries about how the trials that are endured throughout Hours affects his health.
Seth is very close to Olive. Through a encounter when they were younger he has promised to never express any romantic interest in her, even though he very much wishes to.
Seth's pride has caused a few issues. He insulted Olive and Fuzz when he felt his control was being threatened. He has been shown to be insensitive to the feelings of others at times when his thirst for knowledge overrides his better judgement, such as interrogating Olive over her wrist marks instead of asking after her well being.