The Internet has totally blurred, if not altogether obliterated, the lines of good punctuation. Now, people are using punctuation to make little faces at the end of the sentences. This is not the use for which punctuation was originally intended, and it's darn confusing. Maybe that's why it's so difficult to know when to use brackets in fiction writing. It's almost never okay for authors to do so...even when you're writing about what happens on the Internet.
Thou Shalt Not Use Brackets
Brackets are not a parenthesis...they're the more twisted cousin. While parentheses have gently curving lines, brackets have hard edges. That's to remind you that they're used only in the most extreme of circumstances. In fiction, they're used almost ever.
In other types of writing, brackets can be used for a handful of different reasons.
- Math: In some complicated mathematical problems, brackets are used to show specific number groups or functions or what-have-you.
- HTML: Look at an HTML how-to anything online, and you're likely to see brackets. They're commonly used to show how the code is written.
- Quotations: Brackets are found in online articles and other pieces that contain quotes. When a word needs to be added or a pronoun needs to be changed to a proper noun, the word is put inside brackets.
- Direct address: The direct address is the only time you're likely to see brackets in fiction writing. As the name would suggest, this is when the author directly addresses the reader with the words inside the brackets. This by no means requires that you have an entire conversation with the reader. It's usually one to three words at most. It's always done to clarify or emphasize. Example: "Bob and Hugo stared on in shock. He [Hugo] decided to open the umbrella."
Fiction writing doesn't necessarily need brackets, because there are much better ways to clarify what you mean. Using them can help streamline and save time where otherwise a long explanation may be required. Brackets definitely have their place, but like any good punctuation they have to be used sparingly and correctly. Use too many, and it will just become disruptive.