Today’s device…. the POV character commenting on another character’s unusual remark.

Probably the most common way of using this is for the POV character to “explain away” the secondary character’s odd remark by making a philosophical claim.

In Joe Haldeman’s The Forever War, Mandela the POV character’s fellow soldier is wounded. A medic’s reaction is in quotes; Mandela’s comment comes afterward:

“She’s very pretty.” A remarkable observation, her body torn and caked with crusting blood, her face smeared where I had tried to wipe away the tears. I suppose a doctor or a woman or a lover can look beneath that and see beauty.

And if the common move is to explain odd remarks by means of philosophical claims, its flip-side might be to use the move to ironically deflate philosophical claims. In Enrique Vila-Matas‘ Never Any End to Paris, two policemen search the narrator’s room and find out he’s a writer…

The two gorillas searched the garret, saw that no one was making bombs there, took a long look at The Assassin, and finally the tall gorilla asked me if I’d read any Simenon. I didn’t know what would be the best thing to say and decided to tell the truth, I said I hadn’t. “Well,” said the short gorilla, “we’ll be leaving now.” They seemed to be in a good mood all of a sudden, as if they’d managed to get out of an awkward situation. And, although they didn’t apologize to the innocent young man whose lunch they’d interrupted, the short guy did something quite thoughtful once they’d left the garret and were out on the landing on their way to the stairwell. He turned around suddenly and with all the ironic kindness a policeman is capable of, said: “Living alone in a dive like this is not such a good idea.” And the other policeman added: “It’s not good to live alone in the dense solitude of criminals.” This last came quite as a surprise. It was a strange sentence to hear spoken by a policeman, or by anybody for that matter. Anyway, did he think because I was writing about a lettered assassin I was potentially a solitary criminal? Many years later someone told me that “the dense solitude of criminals” was an expression Simenon often used.

Enrique Vila-Matas

I can also imagine various elegant uses of this device for characterization and secondary worldbuilding. Like this:

Detective Billings hesitated, then added: “The fact is, it’s a horrible law.”

“I never thought I’d hear a cop admit that,” I said.

Or like this:

“It’s a shame your timeline has ended here,” the cloaked figure gloated. It was a strange thing for a Timeline Assassin to say.

In both these cases, the device depicts violated expectations, thus allowing the normal set of expectations to appear by implication.

And I think coming up with lines like these is also a useful thought exercise for building secondary worlds: what lines, for instance, would sound weird coming from a thief, a con artist, a factory worker, an alien in your setting…? If you think the question through, you may be able to create a convincing feeling of depth.