Who is Rudy from This House of Sky: Landscapes of a Western Mind and what is their importance?

Rudy was one of McGrath's longest term ranch hands. He related to his boss in a discernible manner. He just told the man 'yes, you're right' regardless. In spite of his indiscriminate use of the term 'Yes' to McGrath's face it was a well known fact that the moment he was off he would do whatever chore seemed most pertinent to his repetoire of skills. He may well have taken into account what McGrath told him but the feeling that he left others with, according to the author, is that just because he told his boss 'yes' didn't necessarily mean that's what he would do.