Sonny is Persephone Hadley's boyfriend in the Noughts And Cross' book: Checkmate (the 3rd book in the series). Sonny and Persephone write songs for other artists together as a job. Persephone's daughter (Callie Rose Hadley) took a liking to Sonny when she was little, as she saw him a lot. One day Sonny asked Callie Rose if he could marry her mum (Persephone). Callie Rose said yes and that night, Sonny asked Persephone to marry him.
She politely declined, and the couple split up. Later on in Checkmate, Persephone gets a job to sing in a restaurant. When she is singing she notices Sonny is at the restaurant with his new girlfriend, so she ignores him. Then he follows her as she goes to get dressed and they start to make out. Sonny's girlfriend catches them and Sonny runs after his distressed girlfriend.