I need three personality traits for Johnny Cade and a supporting detail for each trait.
Johnny Cade is practical; he uses common sense in crisis situations. After recovering from the initial shock of stabbing the Soc in self-defense, he begins to plan, "We gotta get outa here...We'll need money...a plan...Dally...Dally'll get us outa here" (Chapter 4). When he is hiding in Windrixville with Ponyboy, it is his idea to have Ponyboy cut and bleach his hair (Chapter 5). And when he realizes how worried Soda and Darry are about Ponyboy, he decides to turn himself in, reasoning the he "got a good chance of bein' let off easy...(he) ain't got no record with the fuzz and it was self-defense" (Chapter 6).
Johnny is also unselfish. He overlooks danger to himself to save the children from the burning church (Chapter 6). He decides to turn himself in when he sees how worried Soda and Darry are about Ponyboy (Chapter 6). And when he realizes he is going to die, his last thought is for Ponyboy, when he tells him to "Stay gold" (Chapter 9).
Of all the Greasers, Johnny is arguably the most sensitive. He appreciates literature and poetry, sharing Gone With the Wind and Nothing Gold Can Stay with Ponyboy while they are hiding out (Chapter 5). He is perceptive enough to recognize the quality of "gold" in Ponyboy, and to realize it is something of rare value (Chapter 9). And Ponyboy himself observes, "Johnny was a good fighter and could play it cool, but he was sensitive and that isn't a good way to be when you're a Greaser" (Chapter 6).
He is innocent, loving, and sensitive.