An author in his book must be like God in the universe, present everywhere and visible nowhere.
When a reader starts a book, he/she is drawn into the story for many reasons. When the book is a piece of fiction, odds are that one of reasons for being drawn in is because it isn't part of/about the reader. It's an escape. A way to live in another place, to see another life. To hear another voice.
It's a wonderful thing, our power to draw people into the stories we write, our ability to help them escape because of their willingness to suspend disbelief for just long enought to drift into our imaginary landscapes. At the same time, it's a challenge, because once that link is made, it's fragile. So fragile that the smallest error could break it.
I call this break the "Hey wait" moment, after the reaction that I have when something stretches my suspension of disbelief too far. As in: "Hey wait, why the hell would the character do this?"
or... "Hey wait, the solution to this apparently insurmountable problem is simple and provided for in the rules of the universe."
Broadly speaking, "Hey wait" moments happen because of two reasons:
Firstly, because the author didn't pay attention or due regard to all of the important details in his/her story. A good example of this would be when the author forces the character into doing something that's clearly against his/her nature. Another one would be plot holes.
The second cause of a "Hey wait" would be the author showing him/herself. This one's a bit more difficult for a writer to catch, because it has nothing to do with the story, plot or characters. It's something a bit more subtle. It's when the story's voice is wrong, e.g. rich florid prose when the view point character is no nonsense or a stark narration when the character's supposed to be a fun loving kid. It's when the dialogue is forced, especially when it's forced to reveal backstory. In other words: the "As you know" dialogues. Those are my pet hates. They truly make me want to tear a book apart.
Another way that a writer can show him/herself is by writing all stories to the exact same formula. I'm not talking about the preference of certain types of characters or themes. I'm talking about telling different stories according to a single pattern. One that if figured out, will ruin any future story by the author. There's a bestselling author who wrote some great stories that I loved, until I worked out how he wrote them. How did I figure it out? Because each one of them is written in a certain way. And I see that way as cheating.
So the moral here: if you want to cheat, go ahead, just don't keep doing it and assume that no one will notice. Unless you don't care.
Repetition of words and/or sentence structures highlight a writer like nothing else on earth.
So when you get around to edits, add some variety, tripple check for realism and plausibility and do anything in your power to camouflage your presence.
Your reader will thank you for it.
What triggers a "Hey wait" reaction when you read? How do you avoid/fix that trigger when you write?