How old are you boys? What adult was supervising you when your stepbrother Shawn kept beating you & punching the great dane for such a long time?
I can and will say what I'm thinking. This dog has clearly been abused and should be removed from this unstable, out-of-control living situation--immediately. No dog should be subjected to this kind of violence. It's to the dog's credit that he waited so long to become violent himself.