We only see creepy Gorry in a handful of chapters, but he plays an important purpose in the world building of the novel. He's a man who captures capaill and rents them out to riders known as "fifths." What this means is that the rider gives Gorry 4/5 of their winnings and keeps 1/5 for themselves… if they live, that is.
He refuses to let Puck be a fifth, what with her being a girl and all. More importantly, he's the one who catches Skata, the crazy piebald mare. Against Sean's wishes, Gorry ends up keeping her and giving her to Mutt Malvern, putting a huge chain of events into play. How would the novel have turned out differently if he hadn't been so greedy that he puts his profits above riders' lives?