Well for the comic, basically Tawdi is my "good", submissive side while Saphine is my naughty dominant side. So they're kind of like the angel and demon on either shoulder in cartoons.
Well, most of the time Tawdi is the loudest voice, mostly because Saphine is indifferent most of the time or I just don't listen to her over Tawdi's long-winded advice. Every once in a while though, Saph takes total control. The imagery of Saph taking over (as she's a Mistress of Bondage after all~) was too good to not to draw~