First things first, you do not have to ask for permission if you want to use my characters, settings or other elements from my stories, both originals and fanfics. I merely ask that you make it clear which parts of your stories are originally mine. So if you want to write a sequel to one of my stories or something containing my OCs, you have to say so in the A/N of your story, preferably with a link. As for other kinds of derivative works:
( More about fanart, fanfic, podfic, sporkings and translations )
And finally: please tell me when you upload any derivative work. You don't necessarily have to, and you needn't be afraid that I'll retract permission or anything like it. I'd simply like to know.