I don't like pitchers hitting batters. I think there should be a bigger penalty than just a base on balls. To make it happen less I think they should get second base, and maybe force the pitcher to bat.
So if a reliever hits someone he has to bat and potentially get hit himself. Or in the AL if a pitcher hits someone, no more DH for the rest of the game and he has to face a 95 mph fastball himself with potential revenge backed behind it.