Quote 34
And she jumped backwards and disappeared under the water and I thought a shark had eaten her and I screamed and she stood up out of the water again and came over to where I was standing […] (113.4)
This is a rare occasion when Christopher (contrary to his claims) lets his imagination get the better of him. Usually he's scared when he doesn't know what's happening. But here, he's scared because he <em>thinks</em> he knows something bad is happening. When his mother returns, he doesn't need to know what she was doing (as long as it wasn't being eaten by a shark).
Quote 35
And then I knew it wasn't a joke and I was really frightened. (167.23)
Christopher has a difficult time determining when people are joking, which makes it especially interesting to imagine him sort of putting his fear on stand-by until he decides whether or not his dad is joking (about killing Wellington the dog). When he realizes his pop's not joking, he makes an immediate (logical, in a way) connection between his dad killing a dog and the thought that his dad would be capable of hurting him as well.
Quote 36
I was cold and I was frightened Father might come out and find me. But I felt safer in the garden because I was hidden. (179.1)
It's really incredible just how quickly Christopher's father becomes a villain. This is the man who has taken care of Christopher for fifteen years, but in just one moment, he becomes someone who Christopher feels might want to do him serious harm.