Helping somebody deal with bereavement?

About a month ago my younger brother [15] lost a friend in a car accident. he has been really down and doesn't talk about it to any one apart from me. i told my parents and they said that he will get over it and as much as i wish i could just let him deal with it i find myself getting more and more involved with it. ever since it happened he has being getting in to lots of fights at school and as we go to the same school its getting frustrating to be dragged out of lesson and hear that hes being in a fight again .also hes being really emotional if anything is remotely mentioned about the accident. I am starting to get concerned because of how long its being since it happened. is there anything i can do?