Stories with unreliable narrators operate on three levels of truth and deception:
1. What the narrator says about himself and the world around him;
2. What others say about the narrator and events that involve him;
3. What the action reveals about the narrator and truth of his perceptions.
This multi-dimensional approach to truth/deception is one of the reasons unreliable narrator stories are so interesting; they construct and deconstruct truth with the layered complexity of a good mystery, no matter what genre the story.
When we read a story, we make a decision to trust the writer and continue reading, or not to trust the writer and to stop reading. This does not mean that readers trust the character or the truth of the character’s narration. Readers trust that the story and characters will entertain them (intellectually and viscerally), while adhering to a set of rules that the writer has set for the narrative. If the rules the author sets for the narrative are consistently applied, and the work entertains, readers will be swept along, ripe for the surprising twists and turns the writer prepares for them.
The general concept, then, is to present the inconsistencies in the unreliable narrator's account with a rational explanation. Facts may be facts, but unreliable narrators are usually adept at spinning those facts to suit their stories. Readers will note the inconsistency but read on, and thus have a pleasurable aha moment when other characters and events reveal that reality is not what the narrator wants it to seem. Other characters might express views of events that contradict those of the narrator, and the events themselves might play out in a way that’s inconsistent with the narrator’s story.
For example, a narrator might present himself to be the innocent victim of speculation in his wife’s disappearance, a view that others don’t share, and that events as they develop don’t precisely support. For these revelations to work dramatically, the narrator must seem credible at the start, or at least compelling enough as a character for readers to suspend their sense of disbelief, and to be convinced, for a while, by the narrator’s version of the story.