Hal possesses a near limitless store of knowledge about virtually any subject or animal species they encounter, as well as being a skilled doctor. This is because he often takes the role of narrator for the parts of the book where vast volumes of explanations are needed for what is occurring. Despite being a genius, he has a poor grasp of human nature that borders on naiveté which was best demonstrated in "Cannibal Adventure", where he could not understand why Merlin Kaggs - whom he had imprisoned for life - would want to kill him.