Cherry and Marcia are with Socs named Bob and Randy. It is Cherry’s boyfriend, Bob, that Johnny kills.
Pony and Johnny meet two nice Soc girls at the movies. At first they do not understand why the girls are being nice. Socs never socialize with greasers. Cherry is grateful to them for interfering when Dally was messing with them, and Marcia seems flattered by the attention. Cherry doesn’t take the drink Dally offers, but Marcia does.
Oh, yeah, we found out why they were without a car. They'd come with their boyfriends, but walked out on them when they found out the boys had brought some booze along. The boys had gotten angry and left. (Ch. 2)
Cherry and Marcia left their boyfriends because they were drinking too much. They decided to hang out with Johnny and Pony, but trouble ensued when they were leaving the theater and saw Bob’s car. Bob and his friends would not be happy to see their girls with greasers.
Marcia was shifting nervously. "What are we going to do?"
Cherry bit a fingernail. "Stand here," she said. "There isn't much else we can do."
"Who is it?" Two-Bit asked. "The F.B.I.?"
"No," Cherry said bleakly, "it's Randy and Bob." (Ch. 3)
Of course, this is what causes the fight that ultimately leads to Bob’s death. Pony and Johnny are jumped later by the boys, who are by then very drunk. Johnny kills Bob defending Pony from them. Then they have to go one the run. Even though it was self-defense, they worry that the cops will not believe a pair of greasers, especially when they killed a rich Soc.
Later, Cherry tells Pony that she feels sorry about what happened and knows Bob brought it on himself. However, she can't feel too badly about Johnny because he is the one who killed Bob. Randy, on the other hand, decides he is done with fighting and doesn't come to the rumble.