He is the oldest of the McReary siblings. He and Patrick McReary are supposedly "the only normal ones in their family", as they do not have any quirks like the other siblings (Gerry being a football addict, Derrick being extremely into mathematics, and Kate being "bratty").
Francis was the first child born to Maureen McReary and Mr. McReary in September 1999. Francis grew up listening to rap, Eminem in specific. He also played Grand Theft Auto as he grew up, buying every game that was released after he was born. His first younger brother Packie, was born three years after Francis was born, in January 2002. Francis was only 2-3 when Packie was born.
Francis and Packie grew a special bond over the years, stronger than his bond with his other siblings, although he still loved them all. Francis still listened to Eminem and played GTA as he and Packie grew up. Francis introduced Packie to these, and Packie was happy, and he loved them both (this explains where Packie gets his love for rap and video games from).
In Sibling Rivalries, Francis wears a black jacket (since then, has changed to a white jacket with black sleeves from Season 7 onward) with uncolored pants, and his beloved black snapback hat. He has an alternate appearance in his three other appearances, wearing instead a striped jacket and now has sunglasses. His pants of course are unchanged.
For the first six seasons, Francis wore an all-black jacket, but was changed to a white zip-up sweater with black sleeves, the change being done to save pen ink, so he was the only McReary sibling to be redesigned overtime. However, Pablo Torres, who wears an all-black shirt and pants, only had his pants no longer colored starting with season 7, and kept the all-black shirt.