Sean was born on the 22nd of February 1996 to his father Paddy Moore and Alma O'Connor. His father was a dock worker and his mom was a housewife. Sean was raised in a poor neighbourhood in Cork, getting involved in petty thefts at a young age, and being arrested multiple times for his aggressive behaviour, despite being very talented in boxing. At the age of 16 he moved with his father to London to train at a well-known gym there, in preparation for an upcoming boxing tournament in Chernogorsk in a couple years. At the age of 18 he went with his father to the boxing tournament, and while there they saw the news that some sort of virus was spreading across the area. They stayed in their flat in Chernogorsk, surviving for a time off of the food they stored, and later from going out to scavenge around the city.