What is the responsibility of the belayer?
This is actually a pretty broad subject, but one you, as somebodys climbing partner really ought to read up on. A user of these forums once wrote: The climbing is exciting but the responsibility of belaying is incredible: if someone’s safety is dependent on my actions, they’re going to have my full and undivided attention. Most experienced climbers report seeing certain common belay errors often, and while not every one of them results in an accident every time, they do often increase the potential for it. HERE, HERE and HERE are some good discussions to read up on.