Tina's #randomwritingtweet #4 - Keep Characters In Check
The door opened. His ex stood in the doorway, arms crossed, and he jumped to his feet. "You make me want to barf."
So, there may not be anything wrong with the sentence above...if this sounds like something your guy would say.
Fiction writing can be easier than real life. You can make up worlds, people, events, dictate what people will do and how they will react, or can you? The answer is: to a point.
In writing fiction, you are at liberty to create a character, give them a dialect, a personality, a look, a history, and a purpose, but once you have done so, you cannot deviate from your creation all willy-nilly.
If you character is calm, uses words sparingly, and only uses pretentious language when he does use words, then follow through--whatever he is faced with. You may have witnessed a scene in your real life, and you might be compelled to immortalize the scene in your book, but this isn't your diary, this isn't your moment; it is your character's moment and you have to stay true to the personality you created.
With that said, there are times when you can legitimately let your character act "out of character". This, can be a smart, skillful, tool used by the author. There might be a time where your character might say or do something completely out of character--for impact. The character might have "had it", he might be at a turning point, or he might be out to rattle another character--making his reaction a tool of the character AND a tool of the author.
When writing, always ask yourself: is this something I would say, or does it just seem like a cool reaction, or would this character actually do/say this? Make sure you're staying true to your character, unless it is, as mentioned above, a deliberate decision on both your character's and your part for some purposeful effect.