Choosing character names proved much more difficult and important than I had first imagined. An author can choose a name at random and run with it--I believe Douglas Adams chose the name "Zaphod Beeblebrox" as an idiotic placeholder name for his galactic president in "The Hitchhiker's Guide to the Galaxy," and the name just stuck. Or, an author can choose a name that fits the character. I chose the name Gwen for its Celtic history, as well as its meaning of "white light," an appropriate moniker for a girl with magic. Aidan means "little fire," chosen both for his magic and his red hair. Ellie came from cycling through lists of baby names until one jumped out at me with her bubbly personality.
Merlin was easier--he came equipped with his own name! His pseudonym was a little tricker, but nothing I couldn't handle. I played around with a variety of names that sounded vaguely like "Merlin," and Merry Lytton seemed to fit. My choice was confirmed during my research for Ignition. Armed with a stack of dusty tomes about fifth century Wales from my university, I opened the top one--published in the early 1900s--to find it dedicated to "Lord Lytton." It tickled me to think of Merry as a Lord Lytton, and I decided it was fate.