"Fan art is often the viewer's reaction to the show projected onto the character". Not a bad summary, that.
This short PBS video examines the world of fan art, and just why people feel the need to spend their time and energy drawing amazing images of characters who someone else aready created and drew.
Refreshingly, it takes a serious look at the subject, examining not only why artists engage in the practice, but how it can help them grow themselves as creators of their own stuff.
Some of the talking heads include internet cat man Brad O'Farrell and some guy called Sam Spratt.