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

Remorse is the leader of a gang of herdsmen searching the outback of Fourecks for a pack of lost racehorses, Remorse encounters the hapless protagonist, Rincewind the Wizzard, riding on a remarkable, short-legged horse, Snowy. Rincewind is en route from Didjabringabeeralong to Bugarup, but is somewhat lost. Seeing the horse climb the vertical walls of a canyon, down and up again, Remorse asks to buy Snowy and Rincewind, terrified by the ride, agrees.