Johnny killed Bob while another Socs was drowning Ponyboy in a fountain. Bob and some other Socs’ jumped Johnny and Ponyboy and they started drowning Ponyboy while Johnny pulled a knife and stabbed Bob. Johnny stabbed Bob because it was the only way to stop them from killing Ponyboy. Ponyboy reacts by getting scared and running to Dally for help.
In addition, a choice made by Johnny affects Ponyboy similarly by Johnny sticking up for the girls when Dally was messing with them and the girls invite them to sit with them. Johnny sticks