The Last Kids on Earth and the Monster Dimension investigates the conflict between humanity and monstrousness and explores what the terms actually mean. Brallier uses both the physical differences between the human and monster dimensions and the internal conflict that Jack feels between his human self and his monster arm to examine this theme. Ultimately, Brallier argues that monstrousness and humanity have less to do with physical traits and more to do with ethical values and choices.

The novel’s settings in both the human and monster worlds are the foundation for Brallier’s exploration of the difference between humanity and monstrousness. At the beginning of the novel, he creates a stark divide between the monster dimension—a grotesque, otherworldly source of the zombie plague—and the human world, which represents Jack’s past life, friendships, and community. However, with the appearance of “rip-tears” between these worlds, the physical and moral barriers between humans and monsters begin to blur, hinting that there is less difference between the human and monster worlds than it first appears. 

When Jack and his friends first enter the monster world, it repels them. Brallier uses grotesque tactile imagery like the feel of a “corpse-raft’s bloated gut” and the smell of “Fruity Pebbles and burnt hair” to exaggerate the physical repulsiveness of this world (96, 99).