Yik was a mischievous young male shrew member of Log-a-Log Luglug's Guosim tribe. His origin was unknown, even to the shrews that raised him, and he had neither a mother nor father.
Yik rode on Mad Maudie Mugsberry Thropple's shoulders when she and the Guosim were fleeing from Gruntan Kurdly's Brownrats. The pestilential young one pulled Maudie's ears, extorting her to greater speeds, and bit her paw when she tried to stifle his loud yells.
Maudie, Yik, and Luglug eventually had to hide in a streambed from the Brownrats by covering themselves with loam. After being assaulted by a grass snake (which Maudie punched, amusing Yik enormously), the three made a run for Redwall Abbey. Luglug, though his going was hampered by carrying little Yik, refused to give him up, even though Maudie could run much faster with him on her shoulders. The Guosim leader was hit by a Brownrat arrow and killed. Maudie successfully brought Yik to safety.