fff is so popular largely because he isn't a big phony with multiple internet personas.
In regards to fatty's personas, I just assume that every fat guy/gal wearing purple is actually fatty fat fat. As far as I know, I still have not actually met Fatty. I sure made a lot of people angry in the meantime though. Side note- the three dudes I would most like to meet from this site are, in no particular order, SD, Sys, and Rusty. But I think there's already a thread for that. Mods?