Who is Cadwalder from The Floating Island and what is their importance?

Vincent Cadwalder is the steward of Hare Warren, which is a boy's dormitory at the Crossroads Inn. Caldwalder was orphaned when his parents were killed at the crossroads. Alone, Gertrude took him in and clothed and fed him his entire life. Cadwalder betrays Gertrude by working for Maruice Whiting, her competitor.