I was trying to come up with an appropriate name for a MUD. Around the same time, Betrayal at Krondor was released as freeware. The main character of the game (or at least the lead for the first chapter) is named Owyn. I liked the name, because it was appropriate not only for fantasy role play, but for pretty much any game I was likely to play, so I decided to take it for myself. Now, Owyn on its own is often taken, but I remembered that Thom Merrilin's nephew in The Wheel of Time is also named Owyn, so I put two and two together and I've been using it ever since. It's only the second screen name I ever came up with, and I now use it for pretty much everything that isn't better served by a play on my real name.