Original Characters in Fan Fiction

Appearance

Once again, your character's appearance should fit the setting. If your character was born in a tree on the forest moon of Endor, he'd better resemble a bear. And not just any bear; in Return of the Jedi, ewoks are bipedal, approximately 1 m tall, and have fur in shades of brown, black, red, and white (1). So your ewok character shouldn't be lime green and as tall as a house. Similarly, if you're writing a Pride and Prejudice fanfic, avoid having Mr. Darcy's even-more-handsome twin brother fight in Wellington's Iberian campaign while wearing hipster glasses and a Beatle haircut (2).

Speaking of even-more-handsome twin brothers, remember that family members generally look at least a little alike (3). It's nice if this similarity is subtle - face shape, mannerisms - but just about any similarity will do. One thing to keep in mind: genetics. For instance, it is unlikely that two blue-eyed people will have a brown-eyed child (4). If you write a story where this happens, your readers will complain. Don't forget, some fictional worlds have their own genetic rules, and you've got to follow those, too. If every time a Baratheon marries a Lannister, the children have dark hair, you probably shouldn't use the word 'platinum' to describe the hair of your own Baratheon-Lannister character (5).

Finally, don't forget that human characters can only have actual human hair, eye, and skin colours. Please, no eyes the colour of ripe tangerines and hair the colour of starlight. For goodness' sake, I don't even know what the colour of starlight is - not all stars are the same colour. This sort of colouration doesn't make your character unique; it just confuses your reader.

1) http://starwars.wikia.com/wiki/Ewok

2) Unless you're writing a time-travel fic. But we'll talk about breaking the rules later. And even then, Napoleon would probably laugh at hipster glasses. Just sayin'.

3) This can be great for foreshadowing if you're planning to later reveal that the OC is a secret child or sibling of a canon character.

4) It is, however, possible. Eye colour in humans is controlled by more than one gene, so it isn't as simple as you're taught in elementary school. If you're confused as to how, there's a great explanation (with pictures!) online here: http://genetics.thetech.org/how-blue-eyed-parents-can-have-brown-eyed-children

5) A Song of Ice and Fire / Game of Thrones: Colour-coded for your convenience! For the record, that weird little genetic quirk drives me crazy. It doesn't make much sense to me. Unless, of course, the people of Westeros are not actually human . . . which would explain a lot, now that I think about it.