Johnny never even thought about killing that Soc, but the Soc had thought about killing Johnny, because he had jumped Johnny before. Johnny had not intentionally wanted to murder this Soc but it just kinda happened since the Socs were out in Greaser territory looking for either trouble or a kill-for-fun. Johnny has been hurt by others before and does not like it one bit, so he would never ever ever want to hurt anyone else.
In addition to using imagery, S.E. Hinton's use of flashbacks provide the r3eader with critical information that demonstrates killing Bob was an act of self-defense, which is why he should be charged as a juvenile. S.E. Hinton's use of metaphors and similes also allow the reader to really see Johnny's initial reaction when he sees the Socs that had beaten him up coming up to him and Ponyboy. In the quote, "Johnny was scared to death. I mean it. He was as white as a ghost and his eyes were wild-looking, like the eyes of an animal in a trap." (page 54) you can totally see the fear spread across Johnny's face. At the beginning of the story, Ponyboy tells Cherry Valance the story of how a group of Socs simply thought that it would be fun to go up and out of their way and jump some unlucky Greaser. The same Soc that had punched Johnny's face in was sticking Ponyboy's head in a fountain, so Johnny knew that if he did not act fast, Ponyboy would end up either seriously hurt or dead. Since Johnny had been jumped by the same band of Socs, he knew that they would not stop until they were fully satisfied with the outcome of their little task. The quote, "Brain cells and connections are only being lost in the areas controlling impulses, risk-taking, and self-control." from Startling Finds on the Teenage Brain states that brain cells are only being lost in the reflexive side of the teenage brain, meaning that teens will often react to things without really thinking it through due to the fact that they are losing brain cells on a daily basis.