I have a bunch of notebooks filled with concepts and drabbles and all sorts of things related to all kinds of stories from RP to those I write (including the one I'm currently writing). So it's not too hard for me to write, just a bunch of simple modifications. Names are the hardest. I just get either something I like or a name out of the freaking Bible, and add for the last name either a word related to the character concept in a foreign language, a reference to whatever was in my mind when I made the concept or an historical figure. Helps a lot. Or just downright skip last names.