Who is Eagle Ribs from Fools Crow and what is their importance?

Eagle Ribs is a 24 year old "horse taker" who accompanies Yellow Kidney and his group as scout for the Crow raid. He owns a single-shot gun and his scouting abilities make him a real asset. He goes to the Crow camp ahead of the others and returns with a rundown of the camp layout and guides the path of the raiding party.