Before I was sophiedp I went as zairozo. I started using sophiedp after signing up for FanFiction. I was going to go with sophiedp for dA, but it was already taken and zairozo was the next thing I thought of.
I wanted to make a username that had a common J name (Like my actual name and nickname) but not to where it would be too easy to find my real name out (I likes mah privacy). With this, the other J name was Jim that came to mind. Now I was developing my online username before joining dA, it was for Gaia online to begin with. Ironically enough, I found this site's abbreviation to be dA... then it hit me, Jim-DA (You're supposed to pronunciate the d and a, and not 'da')