You would think that Red would be against violence because of her abusive father and how i...

True but sometimes violence becomes all you ever know until you're taught or told otherwise. And she was just a kid- her mom's dead and her dad's in prison. Keep in mind, we didn't get a full backstory on her so god knows what happened to her/ with her during that period. Not justifying her behavior, just trying to see it from a different perspective.