For the most part, you sell the rights to a character, that is it except for keeping it for your portfolio, it's gone. Clarifing that what you are sellig is the surface of the model, the look, needs to be very clear so you don't have the issue that another character has a similar bone structure but a different look, who owns it. We had these problems in a group I am working with. First one of the guys thought his portfolio rights included being able to show a character on someones site before the new owners had a chance to use her as thier spokes person. That is a no no. And the issur that just because a sold character has the same distinctive cheek bones that a new character doea doesn't make the new character an infringement. The buyers have to understand they are basically buying skin.