Paul O'Riley is Jason's cousin but doesn't appear anywhere in the game nor the series. However in the first Devil's Due mission, a cutscene is shown with Jason and his dying older brother who bled to death from a gunshot, which could've been from Frank's mafia or another rival biker gang since he was wearing a biker jacket. Vera knows Paul and calls him Paulie as a nickname and this helps Jason join the Montello Mafia in the first place. his fate is unknown, possibly he is killed by Frank Montello's own hands.