Marley Kelly is the first son of Rose Kelly, she had him at age 16. He is often like the father of the family. He was born in 1992.
He has one little brother Earl Kelly, who is in jail for murdering his girlfriend, and one little half-brother Prince Kelly who is six years old.
He also has two deceased siblings; one little half-sister, Sambuca Kelly, who died in 2012 at seventeen, from a brain tumor, and one little half-brother, Denzil Kelly, who died at fifteen, after being hit by a truck when the school was moving to Scotland, some months after Sam.
After his short time at Waterloo Road, Marley left for university.
As the eldest Kelly child, Marley finds himself trying to act at the head of the family and due to the lack of a genuine father figure in the kids’ life, he become fiercely protective of his sister, Sam and tries to be dad to his family. He knows Earl is a lost cause, perhaps even fears him, but is desperate to keep Earl and Denzil separate so that Denzil stands a fighting chance. Though critical of his family, he’s loyal and won’t hear a bad word said about them from anyone else.
After the arrest of his younger brother Earl, Marley's relationship with Flick blossoms but her dad stands in their way. Ralph Mellor has a strong distaste for the Kelly family and even moreso with Marley, as he feels he is leading his daughter astray. When Flick tests positive on a drugs awareness day that Ralph has facilitated, he tries to shift the results to Marley's profile but he is soon found out and forced to step down as Chair of Governers. Later on when Marley is in need of money due to his family's eviction from Tom Clarkson's road, Ralph offers him £5000 to stay away from Flick. Due to his family loyalties Marley accepts the bribe, but later on Marley can resist Flick no longer and after throwing the money back in Ralph's face, Ralph attacks him with a golf club and despite being a dectective-inspector himself, he is later arrested for knocking down part of the school with a digger.
After these events, Marley consoles a distraught Flick outside the ruined school as her dad is taken away in the police car. Marley graduated after this episode and he and Flick go to university where they continue their relationship.