Many perfectly decent stories have been written, for example, about the future children of the Buffy characters, but you won't find many of them here simply because the subject doesn't interest me very much. I will, however, have links to other fanfic sites. The fan fiction writers just play there. All fan fiction is copyrighted to its respective authors. If you use another author's ideas, or if you write a cross-over story, make sure you cite your sources.
Plagiarism is illegal and discourteous in the extreme.
I may proofread them and correct punctuation, formatting, spelling and grammar if necessary.