Narrative voice is both a strength of “The Sideways Life of Denny Voss” and a thorn in its side.
The title character is the narrator. Almost 30, he is neurodivergent and he lives with the woman he believes is his mother (from the beginning of the book, there are hints he may be wrong), who helps him cope with developmental disabilities he sustained at birth. Novelist Holly Kennedy says in an afterword that she cobbled together the voice from observing relatives with similar challenges and from her own mental health issues, which include anxiety and ADHD.
For the most part, Denny’s voice is charming. Kennedy is giving us privileged access to the brain of a person we might not otherwise encounter, one whose worldview gives us a unique perspective on the human foibles of everyday people.
Often, Denny reports to us on something he doesn’t completely understand — why, for instance, the world considers him “disabled” when he’s also always been told he is “enough” — and the gap between his understanding and ours provides a fascinating space to think about how we sometimes “other” people who simply see things differently than we do.
Kennedy cites Mark Haddon’s “The Curious Incident of the Dog in the Night-Time” in that afterword and there is a similarity between that mega-seller and “Denny” (although I’d say the latter is more akin to lightly sentimental books such as “A Man Called Ove”). Like “Curious,” “Denny” hinges on something puzzling that the narrator can only go so far toward helping us unravel. In this case: Why is Denny in jail for allegedly murdering his neighbor and why was he apprehended with a container full of guns?
We’re sure Denny is innocent, so it remains a sweet tale, with the kindness Denny encounters outweighing the occasional meanness. But Denny’s voice sometimes grates, particularly in the too-often-repeated tic of constantly using parentheses to explain to us the meaning of words such as “lyrics” and “suicide.” The tic may be realistic but Kennedy overuses it long after she has made her point, with as many as five examples on some pages. Eventually, she essentially teaches us to ignore any information that appears in parentheses — which is too bad, since a few of the parenthetical expressions do reveal more about Denny’s wry sense of humor.

One other element of “Denny Voss” that doesn’t work is its setting. Kennedy is Canadian but wanted to insert a (rather heavy-handed) message about gun control. Guns aren’t a huge problem in Canada, so Kennedy set her book in a small town in northern Minnesota but apparently forgot to have someone read the book to check for Americanisms. We do not, for instance, use the phrase “publication ban” in the way Canadians do. We also are more apt to call it a DVR, not a PVR.
“Denny Voss” is still worth reading because of its indelible main character. It’s just that some of the other stuff goes a little sideways.