I'm very familiar with this story from Bradbury's "The October Country." It involves a boy who has an undisclosed illness. He seems pretty vibrant in general, so we are not privy to the symptoms. While other kids go to school, he remains in an upstairs bedroom. He has a dog named Dog who is his emissary; that is, the dog simply runs around doing dog things, but in the process he brings smells and small items from the neighborhood. He is the connection to the outside. One day the boy puts a metal tag on the collar asking for friends. The teacher he would have had discovers the tag and comes to see him. She develops a loving relationship with him, bringing him books and making them come to life. Unfortunately, one day she is killed in a car accident. Dog has one more task and it brings about quite a conclusion. This episode banks on he images of childhood again with beautiful fall images and a kind of magic.
Review of The Emissary
