|"Stay gold, Ponyboy. Stay gold."|
|— Johnny's last words in The Outsiders, page 148|
Ponyboy described Johnny as "Smaller than the rest, with a slight build. He has big black eyes in a dark tanned face; his hair is jet-black and heavily greased and combed to the side, but it is so long that it falls in shaggy bangs across his forehead. He always has a nervous, suspicious look in his eyes." Johnny reminds Ponyboy of a little puppy that had been kicked too many times. His hair is always greasy, and he wears a dark t-shirt with a sky-blue denim jacket and jeans. He has a scar on his left cheek from when he was jumped and beaten severely by a group of Socs, the gash being left by the rings worn by one of the Socs who attacked him.
Johnny was jumped by Socs about four months before the book began and was severely injured. He received a temple-to-cheek long gash scar on his left cheek, which was caused by the large rings worn by one of the Socs who grabbed him. He had the scar for the rest of his life. After the attack, he became extremely jumpy and fearful, and started carrying a switchblade.
He is first seen after his best friend Ponyboy is jumped on the way back home from the movies and has his neck cut by some Socs, but gets saved by the rest of the gang, Johnny being among them. Later he goes to see a movie with Ponyboy and Dallas and they meet two girls, Sherri (Also known as Cherry), and Marcia. He stops Dally from bullying them. They later meet the girls' boyfriends who take the girls away. On the way home they go to the lot near Johnny's house, and fall asleep. Ponyboy wakes up, realizing that it's past his curfew, and rushes home.
Johnny stays behind and later Ponyboy returns saying that Darry hit him. Johnny comforts his friend, when suddenly five Socs turn up, the same ones that had jumped Johnny during the summer. They've come in revenge for the greasers picking up their girlfriends earlier after the drive-in movie. When they try to drown Pony, Johnny kills Bob with his switchblade - Bob is the one who had beaten him and given him the scar on his face months prior. He is horrified afterwards, sitting near the bloody corpse and against the water fountain. When Pony awakens, he hears Johnny uttering "I killed him...", trembling in fear.
They turn to Dallas at Buck Merrill's party to help them evade the police - murderers in Tulsa get the electric chair, and Pony would get split up from his brothers if he got caught, so staying in town wasn't exactly an option. Dally instructs them to hop aboard a freight train heading to a small town called Windrixville, and to hide in a church on Jay Mountain. He gives Johnny a loaded revolver, 50 dollars to buy provisions, as well as giving Pony a dry set of clothes to replace his soaking-wet sleeveless sweatshirt.
They hop aboard the train, and end up at the church after Pony asks a man the way to Jay Mountain. Johnny and Pony fall asleep in the church, and Johnny wakes up before Pony does, throwing his jean jacket over the sleeping boy to keep him warm and heading into town to purchase supplies, including a copy of Gone With The Wind, hydrogen peroxide, a week's supply of baloney, a loaf of bread and a deck of cards. Johnny wants to cut and dye Pony's hair so they wouldn't fit the descriptions in the newpapers. Pony immediately realizes this upon seeing the peroxide - he refuses, saying that it took him a while to get it the way he liked it.
After some convincing, Johnny cuts Pony's hair and dyes it blonde. He lets Pony cut his hair after, and then they pass time in the church by playing poker and reading Gone With The Wind. Pony recites the Robert Frost poem "Nothing Gold Can Stay" when Johnny comments on the gold and silver in the sky, the mist and the clouds being pretty. Pony says that he remembered it because he never quite got what Frost meant when he wrote it.
Dally arrives soon after, saying that he told the police they were headed for Texas, allowing them to go back to Tulsa. Johnny and Pony are treated to barbecue sandwiches and banana splits at the Windrixville Dairy Queen. There, Dally reveals that the greasers have a spy - Cherry Valance had approached him and said that she would keep them informed about the Socs regarding the impending rumble, and would testify that Bob and the others started the fight in the park, and that Johnny killed Bob in self-defense. When the 3 return to the church, they discover that it is on fire with several kids trapped inside. Johnny and Ponyboy rush inside, trying to rescue as many kids as they can. They get all of them out, but a piece of roof falls on Johnny's back, breaking it and giving him severe third-degree burns.
In the hospital, Johnny will only see Dally, Ponyboy and Two-bit, refusing point-blank to see his mother. He dies shortly after the rumble, telling Pony to "Stay gold."
Johnny is very quiet, not getting in the way of the gang very often. This is a result of constantly being neglected and verbally abused by his mother and beaten by his alcoholic father. He is able to hold his own at a rumble, but distances himself from the running and common conflict of being a greaser as often as he can manage, because of the stigma that follows the greasers. He was nearly killed by a group of Socs one night when he was jumped while walking alone. Since that day the gang always made sure that they kept an eye on Johnny, knowing that they would be less vulnerable if they were at least in a group of two. However, this proves not to be the case when Johnny and Ponyboy are jumped one night after they ran away from their neighborhood. While he was in the hospital he mentions to Dallas that he thought that rumbles were pointless and that they don't amount to anything.