Denno was a mouse who was initially from Saint Ninian's. Other than that, his early life is unknown, but he later moved to the North Shores with Luke the Warrior's tribe. He was gone to gather berries while the rest of the tribe was attacked by Vilu Daskar, and thus escaped the massacre. He participated in the attack on the Greenhawk, and later sailed on the Sayna when it sailed to attack the Goreleech.