Have you ever noticed that you collect people in your life who have shared characteristics? Sometimes they don’t even know each other – maybe it’s a friend from high school, a college roommate, and a coworker who all have something in common. I posted a funny little picture of a bat on my personal Facebook page and tagged it with the people I know who are very fond of bats. Two of them worked with me at my last place of business (albeit in different departments) and the third was in the same Master’s program as me. I know it’s not totally unlikely – I have a lot of animal fans among my friends – but it’s still odd enough to make me ponder.
In another example, my sister and two previous co-workers have the same birthday. Again, just a coincidence, but still an odd thing in common.
There are many people in my life who also share behavioral traits or personality quirks. I’ll have moments where interacting with one person will make me think of someone else I know. Often these shared characteristics are things that I don’t share with the people in question. Perhaps it is simply that my personality is complementary to theirs in some way, making it more likely that I will attract friends who share that trait.
Once again, contemplating human behavior can lead to interesting implications for writing. Anything that you notice about people, particularly the things that make them complex, layered individuals, can be incorporated into writing to build the same sense of depth for your characters.