Who is Dishwater Boggett from Lonesome Dove and what is their importance?

Barely twenty-two, Dish sports a walrus mustache of a yellowish brown color that makes him look older than his years. He earned his moniker by coming in from a dry and dusty trail and, unable to wait his turn for water, had taken the dishwater the cook had been about to throw out and drank heartily from it. Dish had a soft spot for Lorena. He usually frequented Mexican whores, but Lorena was different. Around her he got tongue tied and found himself wanting to buy her presents.