When the two factions of Felis Sapiens built two arks and left Red Dwarf, they left behind those members of their society who were considered sick or disabled. They were abandoned to fend for themselves and slowly started to die off. The Idiot was one of those left behind (RD: Waiting for God). He met and became friendly with The Cripple, another Cat who was abandoned because she couldn't walk properly. They started to come together for companionship and eventually had a child who would grow up to be The Cat.