Oarrin was a Redwall mouse. He constantly picked on Coll but was the model of responsibility to the elders. When Martin's sword fell, he was watching from a window, and made up a story of a dream he supposedly had of Martin the Warrior. He became Abbey Warrior, and when Coll demonstrated his skill with the sword, Oarrin drove him out if the Abbey. He felt guilty about it and later admitted to his crime. He escaped Redwall before the Shadowslayers struck the Abbey, and left to find Coll. He was hit by an arrow from Elledis, and could not move for several days. After beginning his journey again, he met Skipper and his ottercrew, who took him along a stream to follow Coll. In the swamps, he was led into the quagmire by the Slarvis lizards. Skrald the Goshawk saved him. Skrald led him out of the swamps most of the way. Treeslinger and Kalda found him in the swamps and brought him to Coll. When they were attacked an Coll knocked unconscious, he used the Sword of Martin to kill the vermin. Afterward he was accepted as having been forgiven for his past crimes. He was sent with some of the Long Patrol to lead Skipper and his Ottercrew to Redwall Abbey.