I thought Helen might have simply stayed with Stephen and shouted for help, to get Nick back sooner or attract other rescuers. Given that she seems to be quite strong, she might even have tried to help him get back out.

b) being taken prisoner by a maniac who then attempts to feed you to creatures;
I'm a little puzzled how *that* is Helen's fault.
Oh, I'm not blaming Helen for that one at all. Helen really did seem to think she could physically protect at least Nick from Leek. She specializes more in emotional torture. ;-) I just think the others suffer more than Helen does, but she's thoroughly self-centered: she doesn't care what anyone else suffers much of the time. It's all about her.