Ankh-Morpork Guard - Although I respect your fine work with Cmdr Vimes, and I don't really want to be tossed into the Ankh...
But the whole point of my rant/essay is that the stock B1 droids seen in the final two (and possibly all three) films are just as indeendant as any other droid. And that wonky excuses such as a 3PO brain, D2 droid brain, or other extensive tinkering with the background are not needed.
None beyond the typical background you would give a droid character: name, designaton, history, personality, et cetra.
As an aside, if anyone feels the name 'Roger Rodger' isn't creative or characterful, I direct to the stars of the Rouge Squadron novels, the R2 droids named 'Whistler' and 'Mynock'. Y'see, astromechs can't speak and they cling onto the backs of starships. That's creative.
The droids we see the most in the canon are never named, and for the most part are only refered to by there model number not even there individual designation... Artoo/R2 not R2-D2; Threepio/3PO not C-3PO; and the pluckly little R4 that saved Obi Wan.
I think my hardest part will be conveining my newest SW GM to allow droid PCs at all. Jedi, exotic aliens, Sith, even Clone Troopers... He makes everyone welcome, and he makes everyone fit into the story. But he won't allow droids!