As soon as Tom stepped into the room, Pete shoved him against a/the wall.
In writing would native speakers be more inclined to use the definite article here even though we don't know which of the four walls of the room it is?
As soon as Tom stepped into the room, Pete shoved him against a/the wall.
In writing would native speakers be more inclined to use the definite article here even though we don't know which of the four walls of the room it is?
Yes. Here's why.
Where conversations involve more than 2 people, and articles are used, use of the means everyone should know which X, and those that don't will have to ask questions to catch up, or just remember that you don't know which X and need to pay attention to get that information when you can.
In fiction, sometimes the conversation includes you as the reader, the narrator, and the characters in the story.
As soon as Tom stepped into the room, Pete shoved him against a/the wall.
So Pete knows which wall is the wall, and so did Tom (if he didn't, he knows now).
You the reader don't know, but all the writer thinks you need to know right now is that Tom wasn't shoved into any random wall, but rather a wall that both Tom and Pete knew about.