The allegory of the reader
This novel is an instance of artistic metafiction, because the story is about a reader reading a story, but a real life reader is also reading the story, so the story is about the reader, in a roundabout way. Instead of reading a book, the reader is watching a character reading a book, discovering the ways that the relationship between an impressionable person and a powerful work of art could damage the reader. By the end of the book, the metafiction aspect of it has turned into a threat: read at your own peril.
The tattoo artist
The symbolic character is a person of consequence, but not in his society. Rather, he leaves a permanent mark on those who encounter him. This is symbolized in his profession. He is a tattoo artist, which means he doesn't give powerful speeches to a community, nor does he run for office to change the world. Instead, he changes a person one person at a time. This is a symbol reference to the artist himself who wrote the novel, because he puts his mark on people one reader at a time.
The blind man
The question of the blind man's existence in the rising action of the novel is an everyday concern— either there is a man or there isn't—but the quest quickly becomes a journey toward hope, taking on religious aspects. The reader begins to obsess about what parts of the book were literally true, and the quest is religious in nature. The blind man could perhaps refer to God, because if he discovers the existence of the blind man, he will feel a lot better. In this interpretation, he tacitly accepts that if God exists, he must be blind.
Insanity and impressionability
The novel depicts through a character motif that the insanity of this character is his deep sincerity, because he can't just drop something. He takes things so seriously, religiously one might say, so that he loses his mind over consequences. He thinks he sees more order than there is—that's one interpretation. The other interpretation is that insanity is stepping stone between normal life and an encounter of the sublime. Perhaps he is correct about his schizoaffective opinions of life.
The symbolic footnotes
When he finally reads the footnotes of the original manuscript of the symbolic (fictitious) book The Navidson Record, he sees a revelation of doom, and the aftermath of his encounter with the new information is the book's final action. The use of footnotes is an allusion to an epic book with many similarities to Navison's book. Here are some reasons to take this as a reference to Infinite Jest by David Foster Wallace: First, Will Navidson shares "avid" with David's name. Secondly, both are combinations of visual art and words, and both involve photography and videography. The use of footnotes to drive the reader crazy seems like a direct reference to the reader's experience of Infinite Jest and both books seem to be giving strict warnings about the way we allow art and entertainment to influence us. The allusion adds much depth to the book.