I think there is actually a way to kill the small child (if you are into that sort of thing). This happened to me in my 4th game:
I walked around the Black Bishop's temple and stayed right against the wall on the East side. You should see a red dot on your mini-map indicating that there is a monster inside the temple. The kid was following me and when he got close to the red dot (the monster came close to the inside of the temple wall) the monster began attacking the kid through the wall. I watched until the kid was almost dead, then ran away from the wall and the kid followed.
Had I stayed there for another couple of seconds the kid would have had no health left, and should have died... I just could not do it though, I'm too much of a softie <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />