Who takes the Ne-mee-poo to the Old Lady's Country in the novel, Thunder Rolling in the Mountains?

Lean Elk is a respected young warrior of the Ne-mee-poo, who eventually is asked to take over for Looking Glass as the leader of the warriors, acting as one of the Ne-mee-poo chiefs. He is the one who decides to take the Ne-mee-poo to the Old Lady's Country to safety, wanting to protect his people and fix Looking Glass's past mistakes.