What type of character do you like to write the best - the quirky guy or the non-quirky guy (or gal)? Almost every time I ask a writer that question, the answer is: the quirky guy. I'm not surprised. It's always a lot more fun to write about an odd duck than a straight arrow type.
As with all things enjoyable, however, there are inherent problems when writing a quirky character, and one of them is overdoing it. Sometimes, when a character has too much going on, an audience will start to hate him and then the movie becomes about him and not the real story. This, of course, happens in different degrees. I love the movie Willow as long as I don't think about the brownies with the odd French(?) accent. Whenever I rent the film I usually find myself rummaging in the kitchen for a snack when they come on the scene. Obviously my reaction isn't something the writer, director or producer would be happy with. Sorry, folks.
Forgive me for stating the obvious, but a film is a collaborative endeavor. So it's not unusual for a writer to create a subtly quirky person and then have the character go through major changes on his way to the screen. A lot of people have input on how he turns out, from the director to the actor and even the costumer. After all, a character's attire should reflect the time period of the script and his personality, unless his clothing is meant to deliberately deceive.
You may write Mr. Quirky as less-than-over-the-top, but once he gets into the hands of those other people, he may end up being more than you'd intended. On the flip side, you may write him as being much too big and splashy and find that the others pull him back a little. The best you can do is balance the character properly when you write him and make sure his actions fit with the type of movie you're writing, i.e., realistic or total make-believe.
One of the easiest ways I find to obtain balance for a quirky character is to think about people I know. Some of my friends have just one little oddball aspect of their personality that makes them unique. One acquaintance always wears the most incredible, wacky earrings you can imagine. They glitter, they clank, they move with every bob of her head, and they are wonderful! An old roommate of mine used to wear her ballet toe-shoes around the flat whenever she felt her butt was getting a little flabby. She swore walking in them helped tone the gluts. And my Grandfather? Oh boy, this rough old codger would stand outside and yell at the tornadoes (the ones in the distance) that ripped through our countryside during the summer. But the very next minute he'd be inside to coo and chirp at his little blue parakeet, Pogo, while he trained it to take matches out of a matchbox.
Don't just think about the people you know. Sit down and make a list of them and their respective quirks. Make sure you don't include certifiably crazy Aunt Matilda who did that weird electrical wiring job with the weathervane and has been discussed for the past 40 years because of it. No, no, stay away from people like her. Just list your normal friends and think about what it is that sets them apart from other people you know.
Why list your normal friends? Well, remember that old cliché about there being a fine line between genius and madness? The same goes for quirky characters: There's a fine line between quirky and bizarre.
For example, think about all of the wonderful, quirky supporting characters in Casablanca. The movie's flow was never interrupted when they were on screen, they only added to the overall experience. From the chubby waiter to the Russian bartender, they all contributed to the movie, not detracted from it. Keep that in mind when you write. A rough, old guy who defies tornadoes is quirky AND believable, but a rough, old guy who starts shooting a bazooka at a tornado is just plain bizarre.
Many movies that succeed do so mostly because the audience can relate to its characters, no matter where they're from or what their situation is. That's why bigger-than-life heroes have flaws, why everymen are thrown into impossible situations, and temptation is dangled in front of "good" characters. All the same holds true for the quirky characters: On some level we can identify with them. The reason movies like Moonstruck and My Big Fat Greek Wedding work so well is because many of us know those characters ... or are those characters. Of course, the people in these two movies were supposed to be real people and did not possess superpowers or ESP. They were caricatures, yes, but still real. Their quirkiness was not over the top.
So what are you going to do the next time you want to write about someone who's a little out of the norm? Will you make him fun and enjoyable or just plain annoying? The choice is yours.