Graylunk was a male weasel corsair of the ship Waveworm under Captain Conva. He was a member of the crew sent to murder the otters of Holt Lutra and take the Tears of all Oceans. However, he and his friend Flairnose stole the pearls, which were meant to be taken back to Ublaz Mad Eyes, and fled into Mossflower Woods. On the way, the two weasels fought over the pearls and Graylunk killed Flairnose, receiving an awful skull wound in the process. He ended up at Redwall Abbey, where he befriended the old squirrel Fermald, the only resident patient enough to stay with him and apparently the only one who could understand his ravings. Fermald was kind to the injured weasel and attempted to make his life happy and comfortable before his inevitable death. Graylunk called Fermald his friend.
Later, Graylunk wandered into Mossflower to finally die from his grievous injuries. Before he departed, Graylunk repented of his evil ways, despite the wicked life that he had led. Graylunk gave the Tears to Fermald, saying that if anyone came asking for him or the pearls, deny everything. Fermald then hid the pearls Graylunk had stolen throughout the Abbey.