Mixcoatl is sharing the tale of his first hunt. When a monster tried eating both him and his friend. His friend ran, and Mixcoatl stayed. Slaying the deadly Night Axe and burying it. Showing him that he is fated to be a hero. A reward for his bravery.
Now Mixcoatl is set to be a hero, not because of something a heart said. But because he chose to run towards when so many others would have ran away.