When Pony watches Johnny die this affects him because he just lost his best friend. He shows his love for Johnny by saying, "Oh damnit, Johnny, don't die, please don't die..."(149). They are close because Johnny is the pet of the gang.
When johnny kill's bob and saves Ponyboy he is risking a lot. First of all, he could be attacked or killed. He also could be charged with murder
when Johnny tells his mom he would rather see ponny. This show's us that they are like family.