Derivative works are art or writing using someone else’s creations, for example my use of the character Peter Rabbit (1938 creation of Beatrix Potter). The reason I decided to do this is that I have real problems scripting short stories. After years of jotting down possible story ideas that I hated a few weeks later, I decided to lower the difficulty level by writing a derivative story, giving me a beginning –conflict-and end but plenty of room for my own creativity. This really is one of the best uses of derivative “fan-art” projects: focusing on an already successful framework/model allows you to build skills and confidence. Fan creations enjoy a growing amount of acceptance and even respect, so your works can potentially get some attention from other devotees of the original work.
But a well-done, fan creation can take a huge amount of time/expertise and yet not be completely yours. For example, since copyright for an original work expires seventy years after the death of the author, the story of Peter Rabbit (character, names, plot) became public domain (http://klminc.com/intellectual-property/peter-rabbit-loses-copyright-protection ) I have full use of the original plot/characters but will have to share them with every other creator who makes a derivation. Disney's treatment of fairy tales gives you an idea of how a big production company inserts enough changes into their version of a tale to "own" it.
The whole issue of copyrighting your creative works has been discussed on CCAS here: (http://www.christiancomicarts.com/forum/topics/question-about-copyrights ) as well as elsewhere (http://fairuse.stanford.edu/overview/faqs/copyright-basics/ Richard Sims blogs about copyright http://weeklycomicbookreview.com/2010/12/01/copyright-issues-in-comic-books-the-basics/ Weekly Comic Review article by Dean Stell
Two important points of retain ownership are worth repeating: copyright for a work exists from the moment it is created by you; secondly, continually document your creative process with signatures, date marks and, for your master-works, witnesses.