Copyright stuff (for lack of a better term because it's not really copyright)

I know that oftentimes I imagine taking my own twists to fanfictions I've read or mixing two together. If there's any chance anyone in the near or far future wants to use my characters for a fanfic of their own, you have my permission. Just mention in the description that the characters are from my stories (sorry if I sound a bit selfish saying it like that. I won't get angry if you don't credit me, but still, it's almost like plagiarism). Also, it would be nice if you'd let me know. It has nothing to do with permission; I'd just like to see what the story's about.