This is one of my favorite parts of character creation. As I write about a character and throw them into a situation, their quirks start to come out.
For example, I have a character who, whenever she gets nervous or bored, she breaks the split ends off her hair. One by one she sits there and grabs a strand of hair, slides her fingers to the bottom and cracks off the end.
Another one is a character who owns every color of Sharpie marker because when her shoes scuff, this is how she polishes them. She just runs her black marker over the scuff on the black shoe and wallah, the scuff is gone. She does the same when her clothes end up discolored as a result of bleach splashes.
Eating sunflower seeds to the point of knowing where the person has been because the sunflower shells are everywhere. She puts an entire hand full into her mouth and can individually split the shell with her teeth, separate the seed from the shell and spit just those two halves out. She moves the seed to one side of her mouth and starts on the next one, and does this until they are all shelled and enjoys a mouthful of seeds.
Always having to match your underwear to your shirt.
None of the food on the plate can touch.
Spending hours getting the pith off the orange.
Having to brush your teeth before you shower.
What are some crazy and unique quirks your characters have, or maybe even yourself or someone you know?