Who is Scrappy from The Last Continent: A Discworld Novel and what is their importance?

Scrappy is a magical, talking kangaroo on the last continent on Discworld, Fourecks, Scrappy is one of several incarnations of The Trickster, the eternal companion of the unfinished land's Creator. His task is to guide hapless Rincewind the Wizzard in his quest to bring back "The Wet" to a parched and arid land. Only when the drought ends, Scrappy explains, will the time/space anomaly end. Scrappy appears to Rincewind and departs from him through primitive cave paintings.