How has violence changed Johnny and Ponyboy in The Outsiders?

Both Johnny and Pony are afraid to walk down the streets
of Tulsa alone, and both boys have been jumped and badly beaten by gangs of Socs. Johnny
has turned to carrying a knife, and both boys rarely travel without their greaser
friends. In Johnny's case, violence has started in the home, where his father beats him
regularly. Both boys have become hardened by the violence, and when Johnny is forced to
defend Pony by killing Bob, it forces them into hiding. Pony's brothers and friends
believe the hatred of the Socs is changing him for the worse, but Johnny's last letter
to him reminds Pony that he can still alter his life for the better, and Pony takes
Johnny's words to heart.