Interaction

"A little rudeness and disrespect can elevate a meaningless interaction into a battle of wills and add drama to an otherwise dull day." -Bill Watterson

There are a lot of ways to tell what a character's like; by his habits, routines, and internal thoughts. All of those are important, but the way they react to people and their world really defines who they are.

Orson Scott Carr said it best, so I'll paraphrase what he said: 'The more characters you have, the more interactions you have. If you just have two characters, you have two relationships: A to B and B to A. If you have three characters, you have to write about six relationships: how A reacts to B, A to C, B to A, and so on. We don't treat everyone in the exact same way.' (To see exactly what he says, look at the introduction to Speaker for the Dead.)

But how do we interact with our world? Well, some people are passionate about politics and always have an opinion on it. Others are indifferent. We have varying levels of obsession for everything, from tracking its every movement to absolute hatred. Keep that in mind. If you need to similar personalities, like two strong girls, give them different hobbies and hatreds. It can help you and your reader to keep them distinct.

Hope it helped,
Kirah