Deyna was the son of Rillflag and Filorn, brother of Mhera, and ancestor of Churk, Rumbol, and the Skipper in Triss. He was born with a birthmark on his pawpad in the shape of a speedwell flower. As Rillflag had an ancestor who had a birthmark and was named Deyna, the young otter was given that name. As a babe he was kidnapped by Sawney Rath, whose seer Grissoul had predicted that the new Taggerung would be a creature of Redwall Abbey and would have a mark resembling a speedwell.