I assume that you are thinking about Dunstan Cass in this case so I will describe his character.
Dunstan Cass is a younger son of Squire Cass and he is interested in gambling and drinking which is not good for him and the people around him.
He is into manipulating his brother Godfrey so we can say that he is selfish.
He is also arrogant to his friend and family and we can also say that he is evil because he is killing the innocent horse. Everything that he does is for his interest and he would do anything for the money.
