Cosbro was an old rabbit who lived in a log that was well hidden, so he wouldn't be found by Darrat rats in Mossflower Country. His ancestors escaped Loamhedge Abbey with Abbess Germaine and her mice (as told in a poem passed down to him), though he apparently was the last rabbit left in Mossflower (on account of the Darrat's presence in the area). Not much else is known about Cosbro, but he dreamed of climbing when he was young, and gave a rope to Bragoon and Sarobando that later proved to be useful in their quest.