Who is Nathan Torrence from Montana Sky and what is their importance?

Nate is Jack Mercy's attorney, neighbor, and long time friend of the Mercy family. As such, Nate is tormented when he is forced to reveal the details of Jack's will to Willa. Nate is also appointed to oversee the operations of Mercy Ranch for the year that Willa runs it while the sisters fulfill the terms of the will. Like Jack, Mate is also a rancher.