Tropes are, in a basic sense, the building blocks of stories. These can be character archetypes (Rogue Cop, Magical Negro); plot devices (The Catch-22 Dilemma, Ticking Bomb); types of joke (Inside Joke, Call-Back). More or less anything that goes into a story.
It was a dark and stormy night, and Alexander sat silently at his desk, gently filing away at the wooden model boat in his hands. A former soldier, he had returned from battle relatively unscathed, but nights like tonight, with thunder crashing across the skies, brought back bad memories.
Focusing in on the creation in his hands, he shaved loose excess wood until the curves of the hull were just right. As always, he found that this focused him, distracting him from his worries and rooted him in something more practical. Suddenly, his head jerked upwards, and he turned around.
“Oh, hello,” he said flatly, his lack of enthusiasm clear to all who had broken into his study.
There was no response, which he found even more unsettling than the storm.
“I know you’re there,” he said. “Watching over me, listening to my thoughts. It’s creepy.”
He really did find it creepy, for he was a private person, who disliked having others peer into his inner life in the way that we were doing. Alexander tried to continue, but his focus was no longer on the boat. Agitated, he couldn’t concentrate on his woodwork, he could barely even sit still in his seat.
“You going to say anything, or just hover there?” he asked, to nowhere in particular. He knew the reader was listening to him, but had no idea what physical position they occupied.
“You can actually hear what I’m thinking, can’t you?” Alexander asked. “Do you have any idea how creepy that is for me?”
He was looking up from his desk, but had no idea where to look. “Well, are you going to talk back, or not?”
Slowly, made uncomfortable by this unconventional stylistic choice, the disembodied reader backed away, leaving Alexander to endure the thunder alone, accompanied only by the terrors of his mind.
“Wait, don’t go!”
Generally, the Fourth Wall Greeting is a comic trope, which makes sense given how silly it is – Stephen Colbert and The Simpsons’ Troy McClure being two of the more notable users of the trope. (The 138th episode spectacular features the show returning from an advert break to find McClure asleep on the couch.)
It seems to be almost universally a television and film trope, which makes sense – it feels like an exaggeration of a chat show or documentary’s attempt to create a casual atmosphere. The example that comes most immediately to mind, for me, is in the beginning of the video for the Bing Crosby – David Bowie collaboration Little Drummer Boy.
Although I’m not familiar with the examples cited by the TV Tropes website, apparently the trope has been used straight in commercials and children’s shows, both of which seem to have a similar level of faith in the audience’s intelligence.
The trope works best, in my opinion, when used in a way that shows faith in the audience or reader’s intelligence, delivered in a way that twists the boundaries between the introduction being used in a knowing, ironic way, or in a straight, cheesy manner.