Sidestories, unlike continuing chapter-released fanfiction, are fanfic stories written like a larger fanfic, but are much shorter. These are usually done to express the author's views on a certain coupling, or a certain idea that was passed down in the series without taking up a great deal of time. Personally I love writing little stories like these- they make for great requests and you can basically do what you want in them without bringing in the main plot from the larger story or anime. ^^
