Chugger was an orphan infant male squirrel with no family. He was kidnapped by a group of Flitchaye and would have presumably been eaten had it not been for Martin the Warrior, Dinny, Gonff the Mousethief, and Trimp the hedgehog who rescued him. When Chugg met Garraway Bullow; she asked the little squirrel what he was doing alone and he told her his story: He'd lived in the forest with his grandmother, but one day, his grandmother 'went to sleep.' Chugger shook her but she didn't wake up; so he was on his own until his kidnap and rescue by the four travelers.
Trimp looked after Chugger as if he were her child. Chugger was later kidnapped again by carrion crows, but he escaped with the help of Krar Woodwatcher.
Chugger changed Folgrim the otter completely and they eventually became very fond of each other. He had no fear of Folgrim, despite the otter's frightening appearance. When Martin and his friends brought Vurg, Denno, Dulam, and Beau back to Redwall Abbey, Chugger adopted them as his four grandpas. While there Chugger quickly befriended Baby Gonflet, who taught the squirrel the art of pie stealing. He and Trimp were taken into Gonff and Columbine's family.