oddness. A singularly focused individual is almost always a 'character,' you know? On the eccentric side.

My take on this is the folks you are talking about giving nerddom a bad name are the ones who are so, uh, nerdy in their pursuit of choice that they have a hard time relating to folks who DON'T appreciate their preferred obsession. As you say, they let their obsession define them.

The comics diehards and the anime otaku are the definitive character studies, but I'm convinced that the archetype can apply to any hobby taken to extremes. I dabble in lots of different hobbies, and far & away the weirdest folks are the really serious gardeners, with the old-time musicians running a distant second.