Who is Deets from Lonesome Dove and what is their importance?

Deets is a large black man with very white teeth. He wears pants made from old quilts that have cotton ticking that sticks out all over the place, and an old cavalry cap that he had found somewhere back in the fifties as close as anyone could remember. Deets wasn't the type to give up on a garment just because it had a little age. He was once given a sheepskin coat found by the Captain after settlers had cleared out and left it behind. The Captain gave it to him mostly because the Captain figured Deets would be the only one strong enough to carry it. It weighed almost as much as a fully grown sheep, and Deets wore it for fifteen years. Finally, it was so full of lice that Gus made Deets sleep in the barn, and one day when he and the Captain were out on the trail, Gus stole it out of the barn and burned it. He told Deets that a buffalo hunter had come through and stolen it.