I think it's kind of interesting, how most of the people on this comm have seen F and L as J and W, everybody loves them at it, and they make great icons, yet we can still have lots of different body images in mind.
I tend to avoid descriptions in my fic, figuring most people already know what J and W look like, at least to them.
Though in my mind, Claude and Eustace look more like the Weasley twins from Harry Potter than the guys in the series, lol! Gingers ahoy!