I'm not sure exactly which 26 pieces you're referring to. However, in general, Sherlock fanfiction can range from mystery - solving adventures that Sherlock embarks on alone, to his interactions with other characters like Mycroft. Some fanfictions might also give a different backstory to Sherlock, making him more human and relatable.
Since I don't know the specific 26 pieces, it's hard to recommend directly. But Sherlock fanfiction usually has a lot of creativity. Some might rewrite certain episodes from a different perspective, like from the point of view of a minor character. Others could be set in an alternate universe where Sherlock has different abilities or the whole London setting has a different feel. It really depends on the author's imagination.