To answer your question BL2033, Sondheim is named for a famous composer for film and stage. He composed one of my favorite plays.. Sweeney Todd. I like naming my fish from movies, plays, writers, actors, artists, etc and it just seemed to fit him. http://en.wikipedia.org/wiki/Stephen_Sondheim
Oh wow! I knew the name sounded familiar! I remember my parents talking about Stephen. (One of the most amazing people by the way.) Created true art!
:Reply to Update:
I especially like the first picture because his mouth is extending a bit and it looks cute. I've seen it plenty of times, just not (captured) at that angle.