Final answer:
Bravery was an important quality that Plains Indians valued in their warriors. They were expected to demonstrate bravery and skill through the concept of counting coup, which involved touching a live enemy and living to tell about it.
Step-by-step explanation:
The important quality that the Plains Indians saw as very important for their warriors to possess was bravery. Warriors were expected to demonstrate bravery and skill through the concept of counting coup. The most highly valued coup was to touch a live enemy and live to tell about it. Killing an enemy was also considered a form of coup, but touching a live enemy demonstrated bravery to a greater degree.