Described by Ponyboy as "a dark little puppy who has been kicked one too many times", Johnny Cade is a product of abusive, alcoholic parents, and has sought refuge in the group known as the "greasers", although that association did not prevent him from being viciously attacked by the rival gang, known as the Socs. When the reader meets Johnny, he is suffering from what today might be called post-traumatic stress disorder; he is jumpy and constantly on the defensive, alert to the possbility that he might be attacked again. Ironically enough, however, it is Johnny who tells Dally to stop harassing the Soc girls at the drive-in; although Dally is likely the most dangerous of the greasers, he is also the most protective of Johnny, and Johnny alone is the one who can tell him what to do.
The fact that Johnny stood up for the Soc girls gets their attention, and they leave the drive-in, walking with Ponyboy and Johnny--which gets the Soc's attention, and sets the novel up for the oncoming story arc: the Soc's attack Ponyboy and Johnny, Johnny kills one of the Soc's, and the two boys go into hiding in a country church not far from where they live. There, Johnny and Ponyboy courageously save some children from a fire, and Johnny is critically injured.
This is where the reader sees enormous strength of character in Johnny, as he lies in the hospital dying. He tells Ponyboy that saving the little kids was worth it, that he feels like his life has finally had some purpose and meaning, and he advises Ponyboy against a life of cynicism and violence, instructing him to "Stay gold", an allusion to the Robert Frost poem the boys had read while hiding in the church. Because of Johnny's final wishes, Ponyboy is inspired to write the story of his gang's tragedy in the hopes of helping other young people who might be experiencing the same social problems.
Johnny needed the protection of the greasers, there is no doubt; however, the greasers needed him just as much, because it made them feel good that they could protect at least one person from the dangers of the Soc's. It gave them a purpose for existing, and helped them avoid thinking about the hopelessness of the lives they were living. However, the ultimate irony of the novel is that the greasers' most helpless member turned out to be the one with the greatest strength of character, the one who left a positive legacy behind in a life cut short too soon.