Subverted: For the first Act of the story, the narrator does nothing but follow more plot relevant people around... Until he reveals himself as the master detective everybody's been expecting to arrive next week.
He in fact reveals himself as the master detective's twin brother, and the master detective arrives as planned.
He reveals himself as the master detective everybody's been expecting to arrive next week... But then one of the people he's been following solves the case before he does.
A case solved by the master detective, as imagined by a hobo who was snooping outside the detective's base, and only saw, not heard, the proceedings... As told by a louse atop the hobo's scalp.
The master detective is stumped for an hour. At the end, the hobo takes the case and solves it in twenty seconds.
So many people reveal their "true" identities and the story changes perspective so many times it's almost impossible to know which characters are which, let alone identify the narrator.
The narrator is set up as a detached, albeit somewhat snarky third-person narrator, but is later revealed to be one of the characters, and one of the main characters at that.
The protagonist and the narrator are one and the same.
Or, the story isn't told in the first person to begin with.
Enforced: "We don't want the audience to be let in on what the protagonist is thinking, so we made the narrator a side character."
Lampshaded: "You might be thinking this story is about me. It's not."
Invoked: "We can't have the protagonist die if he's the narrator! We'll have... Jimmy, the whorehouse eunuch, be the narrator."
Exploited: The detective is able to focus on solving the case rather than writing everything down in a story.
Defied: "You might be thinking this story is about me. It is."
Discussed: "You ever read Moby-Dick? Well, I expect to be like Ishmael: The guy who tells this story to a later audience. That's why I'm pestering your men for more information, not because I'm particularly interested in troop movements."
Conversed: "The protagonist in these stories is always some nobody."
Deconstructed: The narrator gradually realizes his relative unimportance to the story, provoking a crisis of self-image...
Reconstructed: He then realizes no one would hear the story if it weren't for him, and cheers up.