What's your trick for writing an OC that the reader will give a chance?
Well, of course there's no way of knowing which readers will give what story elements a chance. Have the readers who have read my OCs really given them a chance or merely tolerated them? I have no clue unless the OCs are mentioned specifically in reviews.
I have written a lot of OCs in my day, though. If there's a "trick" I employ, it's that they are always support characters, never leads, and they are typically reflection characters of the lead. I use OCs for balance, and to provide a fresh perspective that cannot be given using established characters without succumbing to contrivance or cliché -- that's a lot worse than an OC, if you ask me.
How do you prevent Mary-Sueisms?
Easy answer? Don't write them.
Not so easy answer? Always take care to make sure your characters are realistic and imperfect, and take extra care not to write a character who too closely embodies your personal feelings and does all the cool things you wish you did.
An obvious self-insert will frequently make the worst Mary Sue/Gary Stu imaginable. The writer doesn't realize how obvious the self-insert is, but even strangers reading it can tell. Use a friend, a sibling, a celebrity or a composite -- anyone external as a model for OCs, and then remember that realism and imperfection are key.
How do you integrate your original characters with the existing world?
I usually introduce them when they're off-page. I demonstrate that the lead is aware of the OC, interacts with them, but I don't force that on the reader immediately. Then when the OC finally appears in person, the reader has an awareness of him/her as they're already "part of the story." Then, like I said, I use OCs for support of the main threads of the story, to draw out some aspect of the lead's personality or perception of current events.
For example, in the Gaara fic I'm writing there are two OCs. One is an older villager who is a tradesman (a Narutoverse version of a Muggle, lol), and a little boy. They both interact with Gaara in significant ways, and are part of how the plot moves forward, but they are peripheral and their existence is introduced as part of the background story.
I'm not objective enough to say how effective they are, but you could ask
Dragunov. I think he's the only person on the board who has read this particular fic.
Overall, I'd say that if you're serious about writing don't avoid OCs. After all, writing something original is all about OCs, right? Adding an OC into a fic set in an established universe is good practice for learning how to create an entire story full of them.
P.S. Interesting questions!
Edited by KnS, 17 June 2012 - 12:16 AM.