In this book, the balance of masculinity and femininity is in crisis. As an androgynous person, Frank suffers a sense of imbalance, because there is no clear avenue for him. In the end, we learn that Frank's father has been slipping hormones for hormone replacement therapy in Frank's food, adding even more confusion to the role of gender, but the clearest image is Frank's impotence itself—the man whose genitals were eaten by a dog.
Since the dog is a sign of nature, Frank can consider himself perfectly impotent by nature itself. This makes him something of an archetype, but instead of being a hero, we see that Frank has clearly become archetypal in the wrong direction. Instead of applying his scientific mind to the issues of justice or the common good, he applies his scientific mind to the study of pain and torture, and to his experimentation of chance and fate.
Frank is obsessed with fate because his injury comes with a sense of embarrassment and shame. Now that he is impaired, he must learn to celebrate his capabilities, but because he is embarrassed by the nature of his accident, his perception becomes extremely negative. Instead of seeing his situation with a sense of candor or humor (which certainly would have made him an interesting hero), he fixated on what he could not change, and he became bitter.
Bitterness is interesting in this book, because if Frank is bitter, then who exactly is he bitter with? Well, one could say he is bitter within himself for being at the wrong place at the wrong time. Or, one could say he is bitter with his outward reality, for nature which made the dog with teeth, for the circumstantial timing. But the problem is that those varieties of bitterness don't explain the animal torture. No, if he is bitter enough to torture animals, he must believe that someone is torturing him. He is angry with fate, or perhaps one might say, he is angry with God for allowing such a fate to occur to him, because after all, he was just a boy and had done nothing wrong to deserve it.
