Cycling home with 2 v tired 9 year sons. One braked hard, other careered into the back of him causing minor injury. Fury on the part of injured twin ensued where upon he brazenly attempted to use his bike as revenge weapon. Hence I ordered him off bike until he was calm enough to ride properly and not with murderous intent. I remained v calm but firm but calmness seemed to drive him to ever greater rudeness. Was he trying to see if I would crack? Should I have gone "how very dare you?" strict much earlier on? don't know how to handle him in that mood.