When describing each of the greasers in his tight-knit group, Ponyboy saves Johnny for last. With a metaphor, he compares Johnny, the smallest and one of the youngest of the greasers, to a terrified little puppy:
Johnny Cade was last and least. If you can picture a little dark puppy that has been kicked too many times and is lost in a crowd of strangers, you’ll have Johnny.
While introducing the other greasers, Ponyboy describes Johnny as a "lost" and "kicked" puppy. This simple metaphor gives a comprehensive background to Johnny as a character and helps the reader understand where Johnny comes from. The similarities between Johnny and a "little dark puppy" are not only physical, but also experiential. Like an abused puppy, Johnny is frequently beaten by his parents and jumped by the Socs. Lost in a divided town full of fear and violence, Johnny is constantly frightened and looking over his shoulder for the next attack.
As the smallest greaser, Johnny is an easy target, which only serves to increase his fear. This, in turn, makes Johnny's death the most tragic thing in the novel. Even though he dies as a result of his heroic actions, he leaves the world with fear in his heart.